Migdal et al, Equation (64)

Percentage Accurate: 99.6% → 99.6%
Time: 4.6s
Alternatives: 6
Speedup: 1.9×

Specification

?
\[\begin{array}{l} t_1 := \frac{\cos th}{\sqrt{2}}\\ t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right) \end{array} \]
(FPCore (a1 a2 th)
 :precision binary64
 (let* ((t_1 (/ (cos th) (sqrt 2.0))))
   (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
	double t_1 = cos(th) / sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(a1, a2, th)
use fmin_fmax_functions
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: th
    real(8) :: t_1
    t_1 = cos(th) / sqrt(2.0d0)
    code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
	double t_1 = Math.cos(th) / Math.sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th):
	t_1 = math.cos(th) / math.sqrt(2.0)
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th)
	t_1 = Float64(cos(th) / sqrt(2.0))
	return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2)))
end
function tmp = code(a1, a2, th)
	t_1 = cos(th) / sqrt(2.0);
	tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right)
\end{array}

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 6 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 99.6% accurate, 1.0× speedup?

\[\begin{array}{l} t_1 := \frac{\cos th}{\sqrt{2}}\\ t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right) \end{array} \]
(FPCore (a1 a2 th)
 :precision binary64
 (let* ((t_1 (/ (cos th) (sqrt 2.0))))
   (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
	double t_1 = cos(th) / sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(a1, a2, th)
use fmin_fmax_functions
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: th
    real(8) :: t_1
    t_1 = cos(th) / sqrt(2.0d0)
    code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
	double t_1 = Math.cos(th) / Math.sqrt(2.0);
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th):
	t_1 = math.cos(th) / math.sqrt(2.0)
	return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th)
	t_1 = Float64(cos(th) / sqrt(2.0))
	return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2)))
end
function tmp = code(a1, a2, th)
	t_1 = cos(th) / sqrt(2.0);
	tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right)
\end{array}

Alternative 1: 99.6% accurate, 1.9× speedup?

\[\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{1.4142135623730951} \]
(FPCore (a1 a2 th)
 :precision binary64
 (* (cos th) (/ (fma a2 a2 (* a1 a1)) 1.4142135623730951)))
double code(double a1, double a2, double th) {
	return cos(th) * (fma(a2, a2, (a1 * a1)) / 1.4142135623730951);
}
function code(a1, a2, th)
	return Float64(cos(th) * Float64(fma(a2, a2, Float64(a1 * a1)) / 1.4142135623730951))
end
code[a1_, a2_, th_] := N[(N[Cos[th], $MachinePrecision] * N[(N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / 1.4142135623730951), $MachinePrecision]), $MachinePrecision]
\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{1.4142135623730951}
Derivation
  1. Initial program 99.6%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    2. lift-*.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)} + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
    3. lift-*.f64N/A

      \[\leadsto \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    4. distribute-lft-outN/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
    5. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    6. associate-*l/N/A

      \[\leadsto \color{blue}{\frac{\cos th \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)}{\sqrt{2}}} \]
    7. associate-/l*N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    8. lower-*.f64N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    9. lower-/.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    10. +-commutativeN/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2 + a1 \cdot a1}}{\sqrt{2}} \]
    11. lift-*.f64N/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2} + a1 \cdot a1}{\sqrt{2}} \]
    12. lower-fma.f6499.6%

      \[\leadsto \cos th \cdot \frac{\color{blue}{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}}{\sqrt{2}} \]
  3. Applied rewrites99.6%

    \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  4. Evaluated real constant99.6%

    \[\leadsto \cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{1.4142135623730951}} \]
  5. Add Preprocessing

Alternative 2: 99.5% accurate, 1.9× speedup?

\[\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot 0.7071067811865475 \]
(FPCore (a1 a2 th)
 :precision binary64
 (* (* (cos th) (fma a2 a2 (* a1 a1))) 0.7071067811865475))
double code(double a1, double a2, double th) {
	return (cos(th) * fma(a2, a2, (a1 * a1))) * 0.7071067811865475;
}
function code(a1, a2, th)
	return Float64(Float64(cos(th) * fma(a2, a2, Float64(a1 * a1))) * 0.7071067811865475)
end
code[a1_, a2_, th_] := N[(N[(N[Cos[th], $MachinePrecision] * N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * 0.7071067811865475), $MachinePrecision]
\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot 0.7071067811865475
Derivation
  1. Initial program 99.6%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    2. lift-*.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)} + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
    3. lift-*.f64N/A

      \[\leadsto \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    4. distribute-lft-outN/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
    5. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    6. associate-*l/N/A

      \[\leadsto \color{blue}{\frac{\cos th \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)}{\sqrt{2}}} \]
    7. associate-/l*N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    8. lower-*.f64N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    9. lower-/.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    10. +-commutativeN/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2 + a1 \cdot a1}}{\sqrt{2}} \]
    11. lift-*.f64N/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2} + a1 \cdot a1}{\sqrt{2}} \]
    12. lower-fma.f6499.6%

      \[\leadsto \cos th \cdot \frac{\color{blue}{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}}{\sqrt{2}} \]
  3. Applied rewrites99.6%

    \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  4. Evaluated real constant99.6%

    \[\leadsto \cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{1.4142135623730951}} \]
  5. Step-by-step derivation
    1. lift-cos.f64N/A

      \[\leadsto \color{blue}{\cos th} \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}} \]
    2. lift-*.f64N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \]
    3. lift-/.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \]
    4. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \]
    5. mult-flipN/A

      \[\leadsto \color{blue}{\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}} \]
    6. lower-*.f64N/A

      \[\leadsto \color{blue}{\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}} \]
    7. lower-*.f64N/A

      \[\leadsto \color{blue}{\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}} \]
    8. lift-cos.f64N/A

      \[\leadsto \left(\color{blue}{\cos th} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}} \]
    9. metadata-eval99.5%

      \[\leadsto \left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \color{blue}{0.7071067811865475} \]
  6. Applied rewrites99.5%

    \[\leadsto \color{blue}{\left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot 0.7071067811865475} \]
  7. Add Preprocessing

Alternative 3: 99.5% accurate, 1.9× speedup?

\[\left(\cos th \cdot 0.7071067811865475\right) \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right) \]
(FPCore (a1 a2 th)
 :precision binary64
 (* (* (cos th) 0.7071067811865475) (fma a2 a2 (* a1 a1))))
double code(double a1, double a2, double th) {
	return (cos(th) * 0.7071067811865475) * fma(a2, a2, (a1 * a1));
}
function code(a1, a2, th)
	return Float64(Float64(cos(th) * 0.7071067811865475) * fma(a2, a2, Float64(a1 * a1)))
end
code[a1_, a2_, th_] := N[(N[(N[Cos[th], $MachinePrecision] * 0.7071067811865475), $MachinePrecision] * N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\left(\cos th \cdot 0.7071067811865475\right) \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)
Derivation
  1. Initial program 99.6%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    2. lift-*.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)} + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
    3. lift-*.f64N/A

      \[\leadsto \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
    4. distribute-lft-outN/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
    5. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
    6. associate-*l/N/A

      \[\leadsto \color{blue}{\frac{\cos th \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)}{\sqrt{2}}} \]
    7. associate-/l*N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    8. lower-*.f64N/A

      \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    9. lower-/.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
    10. +-commutativeN/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2 + a1 \cdot a1}}{\sqrt{2}} \]
    11. lift-*.f64N/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2} + a1 \cdot a1}{\sqrt{2}} \]
    12. lower-fma.f6499.6%

      \[\leadsto \cos th \cdot \frac{\color{blue}{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}}{\sqrt{2}} \]
  3. Applied rewrites99.6%

    \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  4. Evaluated real constant99.6%

    \[\leadsto \cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{1.4142135623730951}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \]
    2. lift-fma.f64N/A

      \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2 + a1 \cdot a1}}{\frac{6369051672525773}{4503599627370496}} \]
    3. div-addN/A

      \[\leadsto \cos th \cdot \color{blue}{\left(\frac{a2 \cdot a2}{\frac{6369051672525773}{4503599627370496}} + \frac{a1 \cdot a1}{\frac{6369051672525773}{4503599627370496}}\right)} \]
    4. associate-/l*N/A

      \[\leadsto \cos th \cdot \left(\color{blue}{a2 \cdot \frac{a2}{\frac{6369051672525773}{4503599627370496}}} + \frac{a1 \cdot a1}{\frac{6369051672525773}{4503599627370496}}\right) \]
    5. lower-fma.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\mathsf{fma}\left(a2, \frac{a2}{\frac{6369051672525773}{4503599627370496}}, \frac{a1 \cdot a1}{\frac{6369051672525773}{4503599627370496}}\right)} \]
    6. lower-/.f64N/A

      \[\leadsto \cos th \cdot \mathsf{fma}\left(a2, \color{blue}{\frac{a2}{\frac{6369051672525773}{4503599627370496}}}, \frac{a1 \cdot a1}{\frac{6369051672525773}{4503599627370496}}\right) \]
    7. mult-flipN/A

      \[\leadsto \cos th \cdot \mathsf{fma}\left(a2, \frac{a2}{\frac{6369051672525773}{4503599627370496}}, \color{blue}{\left(a1 \cdot a1\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}}\right) \]
    8. lower-*.f64N/A

      \[\leadsto \cos th \cdot \mathsf{fma}\left(a2, \frac{a2}{\frac{6369051672525773}{4503599627370496}}, \color{blue}{\left(a1 \cdot a1\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}}\right) \]
    9. metadata-eval99.6%

      \[\leadsto \cos th \cdot \mathsf{fma}\left(a2, \frac{a2}{1.4142135623730951}, \left(a1 \cdot a1\right) \cdot \color{blue}{0.7071067811865475}\right) \]
  6. Applied rewrites99.6%

    \[\leadsto \cos th \cdot \color{blue}{\mathsf{fma}\left(a2, \frac{a2}{1.4142135623730951}, \left(a1 \cdot a1\right) \cdot 0.7071067811865475\right)} \]
  7. Step-by-step derivation
    1. lift-fma.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\left(a2 \cdot \frac{a2}{\frac{6369051672525773}{4503599627370496}} + \left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773}\right)} \]
    2. +-commutativeN/A

      \[\leadsto \cos th \cdot \color{blue}{\left(\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773} + a2 \cdot \frac{a2}{\frac{6369051672525773}{4503599627370496}}\right)} \]
    3. lift-*.f64N/A

      \[\leadsto \cos th \cdot \left(\color{blue}{\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773}} + a2 \cdot \frac{a2}{\frac{6369051672525773}{4503599627370496}}\right) \]
    4. lift-/.f64N/A

      \[\leadsto \cos th \cdot \left(\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773} + a2 \cdot \color{blue}{\frac{a2}{\frac{6369051672525773}{4503599627370496}}}\right) \]
    5. associate-*r/N/A

      \[\leadsto \cos th \cdot \left(\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773} + \color{blue}{\frac{a2 \cdot a2}{\frac{6369051672525773}{4503599627370496}}}\right) \]
    6. mult-flip-revN/A

      \[\leadsto \cos th \cdot \left(\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773} + \color{blue}{\left(a2 \cdot a2\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}}\right) \]
    7. metadata-evalN/A

      \[\leadsto \cos th \cdot \left(\left(a1 \cdot a1\right) \cdot \frac{4503599627370496}{6369051672525773} + \left(a2 \cdot a2\right) \cdot \color{blue}{\frac{4503599627370496}{6369051672525773}}\right) \]
    8. distribute-rgt-inN/A

      \[\leadsto \cos th \cdot \color{blue}{\left(\frac{4503599627370496}{6369051672525773} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)\right)} \]
    9. +-commutativeN/A

      \[\leadsto \cos th \cdot \left(\frac{4503599627370496}{6369051672525773} \cdot \color{blue}{\left(a2 \cdot a2 + a1 \cdot a1\right)}\right) \]
    10. lift-fma.f64N/A

      \[\leadsto \cos th \cdot \left(\frac{4503599627370496}{6369051672525773} \cdot \color{blue}{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}\right) \]
    11. lift-*.f6499.5%

      \[\leadsto \cos th \cdot \color{blue}{\left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \]
    12. lower-*.f64N/A

      \[\leadsto \color{blue}{\cos th \cdot \left(\frac{4503599627370496}{6369051672525773} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \]
    13. lift-*.f64N/A

      \[\leadsto \cos th \cdot \color{blue}{\left(\frac{4503599627370496}{6369051672525773} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \]
    14. associate-*r*N/A

      \[\leadsto \color{blue}{\left(\cos th \cdot \frac{4503599627370496}{6369051672525773}\right) \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)} \]
    15. lower-*.f64N/A

      \[\leadsto \color{blue}{\left(\cos th \cdot \frac{4503599627370496}{6369051672525773}\right) \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)} \]
    16. lower-*.f6499.5%

      \[\leadsto \color{blue}{\left(\cos th \cdot 0.7071067811865475\right)} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right) \]
  8. Applied rewrites99.5%

    \[\leadsto \color{blue}{\left(\cos th \cdot 0.7071067811865475\right) \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)} \]
  9. Add Preprocessing

Alternative 4: 78.1% accurate, 0.7× speedup?

\[\begin{array}{l} t_1 := \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\\ t_2 := \frac{\cos th}{\sqrt{2}}\\ \mathbf{if}\;t\_2 \cdot \left(a1 \cdot a1\right) + t\_2 \cdot \left(a2 \cdot a2\right) \leq -5 \cdot 10^{-160}:\\ \;\;\;\;\left(0.7071067811865475 \cdot t\_1\right) \cdot \left(1 + -0.5 \cdot {th}^{2}\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{t\_1}{\sqrt{2}}\\ \end{array} \]
(FPCore (a1 a2 th)
 :precision binary64
 (let* ((t_1 (fma a2 a2 (* a1 a1))) (t_2 (/ (cos th) (sqrt 2.0))))
   (if (<= (+ (* t_2 (* a1 a1)) (* t_2 (* a2 a2))) -5e-160)
     (* (* 0.7071067811865475 t_1) (+ 1.0 (* -0.5 (pow th 2.0))))
     (/ t_1 (sqrt 2.0)))))
double code(double a1, double a2, double th) {
	double t_1 = fma(a2, a2, (a1 * a1));
	double t_2 = cos(th) / sqrt(2.0);
	double tmp;
	if (((t_2 * (a1 * a1)) + (t_2 * (a2 * a2))) <= -5e-160) {
		tmp = (0.7071067811865475 * t_1) * (1.0 + (-0.5 * pow(th, 2.0)));
	} else {
		tmp = t_1 / sqrt(2.0);
	}
	return tmp;
}
function code(a1, a2, th)
	t_1 = fma(a2, a2, Float64(a1 * a1))
	t_2 = Float64(cos(th) / sqrt(2.0))
	tmp = 0.0
	if (Float64(Float64(t_2 * Float64(a1 * a1)) + Float64(t_2 * Float64(a2 * a2))) <= -5e-160)
		tmp = Float64(Float64(0.7071067811865475 * t_1) * Float64(1.0 + Float64(-0.5 * (th ^ 2.0))));
	else
		tmp = Float64(t_1 / sqrt(2.0));
	end
	return tmp
end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[N[(N[(t$95$2 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$2 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], -5e-160], N[(N[(0.7071067811865475 * t$95$1), $MachinePrecision] * N[(1.0 + N[(-0.5 * N[Power[th, 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(t$95$1 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}
t_1 := \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\\
t_2 := \frac{\cos th}{\sqrt{2}}\\
\mathbf{if}\;t\_2 \cdot \left(a1 \cdot a1\right) + t\_2 \cdot \left(a2 \cdot a2\right) \leq -5 \cdot 10^{-160}:\\
\;\;\;\;\left(0.7071067811865475 \cdot t\_1\right) \cdot \left(1 + -0.5 \cdot {th}^{2}\right)\\

\mathbf{else}:\\
\;\;\;\;\frac{t\_1}{\sqrt{2}}\\


\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (+.f64 (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a1 a1)) (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a2 a2))) < -4.9999999999999999e-160

    1. Initial program 99.6%

      \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
    2. Step-by-step derivation
      1. lift-+.f64N/A

        \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
      2. lift-*.f64N/A

        \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right)} + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
      3. lift-*.f64N/A

        \[\leadsto \frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right)} \]
      4. distribute-lft-outN/A

        \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)} \]
      5. lift-/.f64N/A

        \[\leadsto \color{blue}{\frac{\cos th}{\sqrt{2}}} \cdot \left(a1 \cdot a1 + a2 \cdot a2\right) \]
      6. associate-*l/N/A

        \[\leadsto \color{blue}{\frac{\cos th \cdot \left(a1 \cdot a1 + a2 \cdot a2\right)}{\sqrt{2}}} \]
      7. associate-/l*N/A

        \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
      8. lower-*.f64N/A

        \[\leadsto \color{blue}{\cos th \cdot \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
      9. lower-/.f64N/A

        \[\leadsto \cos th \cdot \color{blue}{\frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{2}}} \]
      10. +-commutativeN/A

        \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2 + a1 \cdot a1}}{\sqrt{2}} \]
      11. lift-*.f64N/A

        \[\leadsto \cos th \cdot \frac{\color{blue}{a2 \cdot a2} + a1 \cdot a1}{\sqrt{2}} \]
      12. lower-fma.f6499.6%

        \[\leadsto \cos th \cdot \frac{\color{blue}{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}}{\sqrt{2}} \]
    3. Applied rewrites99.6%

      \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
    4. Evaluated real constant99.6%

      \[\leadsto \cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{1.4142135623730951}} \]
    5. Step-by-step derivation
      1. lift-cos.f64N/A

        \[\leadsto \color{blue}{\cos th} \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}} \]
      2. lift-*.f64N/A

        \[\leadsto \color{blue}{\cos th \cdot \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \]
      3. *-commutativeN/A

        \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}} \cdot \cos th} \]
      4. lower-*.f64N/A

        \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}} \cdot \cos th} \]
      5. lift-/.f64N/A

        \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\frac{6369051672525773}{4503599627370496}}} \cdot \cos th \]
      6. mult-flipN/A

        \[\leadsto \color{blue}{\left(\mathsf{fma}\left(a2, a2, a1 \cdot a1\right) \cdot \frac{1}{\frac{6369051672525773}{4503599627370496}}\right)} \cdot \cos th \]
      7. *-commutativeN/A

        \[\leadsto \color{blue}{\left(\frac{1}{\frac{6369051672525773}{4503599627370496}} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \cdot \cos th \]
      8. lower-*.f64N/A

        \[\leadsto \color{blue}{\left(\frac{1}{\frac{6369051672525773}{4503599627370496}} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)} \cdot \cos th \]
      9. metadata-evalN/A

        \[\leadsto \left(\color{blue}{\frac{4503599627370496}{6369051672525773}} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \cos th \]
      10. lift-cos.f6499.5%

        \[\leadsto \left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \color{blue}{\cos th} \]
    6. Applied rewrites99.5%

      \[\leadsto \color{blue}{\left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \cos th} \]
    7. Taylor expanded in th around 0

      \[\leadsto \left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \color{blue}{\left(1 + \frac{-1}{2} \cdot {th}^{2}\right)} \]
    8. Step-by-step derivation
      1. lower-+.f64N/A

        \[\leadsto \left(\frac{4503599627370496}{6369051672525773} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \left(1 + \color{blue}{\frac{-1}{2} \cdot {th}^{2}}\right) \]
      2. lower-*.f64N/A

        \[\leadsto \left(\frac{4503599627370496}{6369051672525773} \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \left(1 + \frac{-1}{2} \cdot \color{blue}{{th}^{2}}\right) \]
      3. lower-pow.f6463.4%

        \[\leadsto \left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \left(1 + -0.5 \cdot {th}^{\color{blue}{2}}\right) \]
    9. Applied rewrites63.4%

      \[\leadsto \left(0.7071067811865475 \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right) \cdot \color{blue}{\left(1 + -0.5 \cdot {th}^{2}\right)} \]

    if -4.9999999999999999e-160 < (+.f64 (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a1 a1)) (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a2 a2)))

    1. Initial program 99.6%

      \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
    2. Taylor expanded in th around 0

      \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
    3. Step-by-step derivation
      1. lower-+.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
      2. lower-/.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a2}^{2}}}{\sqrt{2}} \]
      3. lower-pow.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a2}}^{2}}{\sqrt{2}} \]
      4. lower-sqrt.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{\color{blue}{2}}}{\sqrt{2}} \]
      5. lower-/.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\color{blue}{\sqrt{2}}} \]
      6. lower-pow.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{\color{blue}{2}}} \]
      7. lower-sqrt.f6466.2%

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}} \]
    4. Applied rewrites66.2%

      \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
    5. Step-by-step derivation
      1. lift-+.f64N/A

        \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
      2. +-commutativeN/A

        \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a1}^{2}}{\sqrt{2}}} \]
      3. lift-/.f64N/A

        \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a1}^{2}}}{\sqrt{2}} \]
      4. lift-pow.f64N/A

        \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
      5. pow2N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
      6. lift-*.f64N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
      7. lift-/.f64N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\color{blue}{\sqrt{2}}} \]
      8. lift-pow.f64N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\sqrt{\color{blue}{2}}} \]
      9. pow2N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
      10. lift-*.f64N/A

        \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
      11. div-addN/A

        \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\color{blue}{\sqrt{2}}} \]
      12. lift-*.f64N/A

        \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\sqrt{2}} \]
      13. lift-fma.f64N/A

        \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
      14. lift-/.f6466.2%

        \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{\sqrt{2}}} \]
    6. Applied rewrites66.2%

      \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 5: 66.2% accurate, 6.4× speedup?

\[\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}} \]
(FPCore (a1 a2 th) :precision binary64 (/ (fma a2 a2 (* a1 a1)) (sqrt 2.0)))
double code(double a1, double a2, double th) {
	return fma(a2, a2, (a1 * a1)) / sqrt(2.0);
}
function code(a1, a2, th)
	return Float64(fma(a2, a2, Float64(a1 * a1)) / sqrt(2.0))
end
code[a1_, a2_, th_] := N[(N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]
\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}
Derivation
  1. Initial program 99.6%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Taylor expanded in th around 0

    \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
  3. Step-by-step derivation
    1. lower-+.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
    2. lower-/.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a2}^{2}}}{\sqrt{2}} \]
    3. lower-pow.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a2}}^{2}}{\sqrt{2}} \]
    4. lower-sqrt.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{\color{blue}{2}}}{\sqrt{2}} \]
    5. lower-/.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\color{blue}{\sqrt{2}}} \]
    6. lower-pow.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{\color{blue}{2}}} \]
    7. lower-sqrt.f6466.2%

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}} \]
  4. Applied rewrites66.2%

    \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
    2. +-commutativeN/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a1}^{2}}{\sqrt{2}}} \]
    3. lift-/.f64N/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a1}^{2}}}{\sqrt{2}} \]
    4. lift-pow.f64N/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    5. pow2N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    6. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    7. lift-/.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\color{blue}{\sqrt{2}}} \]
    8. lift-pow.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\sqrt{\color{blue}{2}}} \]
    9. pow2N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
    10. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
    11. div-addN/A

      \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\color{blue}{\sqrt{2}}} \]
    12. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\sqrt{2}} \]
    13. lift-fma.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
    14. lift-/.f6466.2%

      \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{\sqrt{2}}} \]
  6. Applied rewrites66.2%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  7. Add Preprocessing

Alternative 6: 39.4% accurate, 7.4× speedup?

\[\frac{1 \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
(FPCore (a1 a2 th) :precision binary64 (/ (* 1.0 (* a1 a1)) (sqrt 2.0)))
double code(double a1, double a2, double th) {
	return (1.0 * (a1 * a1)) / sqrt(2.0);
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(a1, a2, th)
use fmin_fmax_functions
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: th
    code = (1.0d0 * (a1 * a1)) / sqrt(2.0d0)
end function
public static double code(double a1, double a2, double th) {
	return (1.0 * (a1 * a1)) / Math.sqrt(2.0);
}
def code(a1, a2, th):
	return (1.0 * (a1 * a1)) / math.sqrt(2.0)
function code(a1, a2, th)
	return Float64(Float64(1.0 * Float64(a1 * a1)) / sqrt(2.0))
end
function tmp = code(a1, a2, th)
	tmp = (1.0 * (a1 * a1)) / sqrt(2.0);
end
code[a1_, a2_, th_] := N[(N[(1.0 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]
\frac{1 \cdot \left(a1 \cdot a1\right)}{\sqrt{2}}
Derivation
  1. Initial program 99.6%

    \[\frac{\cos th}{\sqrt{2}} \cdot \left(a1 \cdot a1\right) + \frac{\cos th}{\sqrt{2}} \cdot \left(a2 \cdot a2\right) \]
  2. Taylor expanded in th around 0

    \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
  3. Step-by-step derivation
    1. lower-+.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
    2. lower-/.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a2}^{2}}}{\sqrt{2}} \]
    3. lower-pow.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a2}}^{2}}{\sqrt{2}} \]
    4. lower-sqrt.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{\color{blue}{2}}}{\sqrt{2}} \]
    5. lower-/.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\color{blue}{\sqrt{2}}} \]
    6. lower-pow.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{\color{blue}{2}}} \]
    7. lower-sqrt.f6466.2%

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}} \]
  4. Applied rewrites66.2%

    \[\leadsto \color{blue}{\frac{{a1}^{2}}{\sqrt{2}} + \frac{{a2}^{2}}{\sqrt{2}}} \]
  5. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \frac{{a1}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a2}^{2}}{\sqrt{2}}} \]
    2. +-commutativeN/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \color{blue}{\frac{{a1}^{2}}{\sqrt{2}}} \]
    3. lift-/.f64N/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{\color{blue}{{a1}^{2}}}{\sqrt{2}} \]
    4. lift-pow.f64N/A

      \[\leadsto \frac{{a2}^{2}}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    5. pow2N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    6. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{\color{blue}{a1}}^{2}}{\sqrt{2}} \]
    7. lift-/.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\color{blue}{\sqrt{2}}} \]
    8. lift-pow.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{{a1}^{2}}{\sqrt{\color{blue}{2}}} \]
    9. pow2N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
    10. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2}{\sqrt{2}} + \frac{a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
    11. div-addN/A

      \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\color{blue}{\sqrt{2}}} \]
    12. lift-*.f64N/A

      \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\sqrt{2}} \]
    13. lift-fma.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
    14. lift-/.f6466.2%

      \[\leadsto \frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\color{blue}{\sqrt{2}}} \]
  6. Applied rewrites66.2%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}} \]
  7. Step-by-step derivation
    1. lift-fma.f64N/A

      \[\leadsto \frac{a2 \cdot a2 + a1 \cdot a1}{\sqrt{\color{blue}{2}}} \]
    2. +-commutativeN/A

      \[\leadsto \frac{a1 \cdot a1 + a2 \cdot a2}{\sqrt{\color{blue}{2}}} \]
    3. sum-to-multN/A

      \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
    4. lower-unsound-*.f64N/A

      \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
    5. lower-unsound-+.f64N/A

      \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
    6. lower-unsound-/.f64N/A

      \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
    7. lower-*.f6443.3%

      \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
  8. Applied rewrites43.3%

    \[\leadsto \frac{\left(1 + \frac{a2 \cdot a2}{a1 \cdot a1}\right) \cdot \left(a1 \cdot a1\right)}{\sqrt{\color{blue}{2}}} \]
  9. Taylor expanded in a1 around inf

    \[\leadsto \frac{1 \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
  10. Step-by-step derivation
    1. Applied rewrites39.4%

      \[\leadsto \frac{1 \cdot \left(a1 \cdot a1\right)}{\sqrt{2}} \]
    2. Add Preprocessing

    Reproduce

    ?
    herbie shell --seed 2025193 
    (FPCore (a1 a2 th)
      :name "Migdal et al, Equation (64)"
      :precision binary64
      (+ (* (/ (cos th) (sqrt 2.0)) (* a1 a1)) (* (/ (cos th) (sqrt 2.0)) (* a2 a2))))