math.square on complex, imaginary part

Percentage Accurate: 56.4% → 56.4%
Time: 1.3s
Alternatives: 3
Speedup: 1.4×

Specification

?
\[\begin{array}{l} \\ re \cdot im + im \cdot re \end{array} \]
(FPCore im_sqr (re im) :precision binary64 (+ (* re im) (* im re)))
double im_sqr(double re, double im) {
	return (re * im) + (im * re);
}
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 im_sqr(re, im)
use fmin_fmax_functions
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    im_sqr = (re * im) + (im * re)
end function
public static double im_sqr(double re, double im) {
	return (re * im) + (im * re);
}
def im_sqr(re, im):
	return (re * im) + (im * re)
function im_sqr(re, im)
	return Float64(Float64(re * im) + Float64(im * re))
end
function tmp = im_sqr(re, im)
	tmp = (re * im) + (im * re);
end
im$95$sqr[re_, im_] := N[(N[(re * im), $MachinePrecision] + N[(im * re), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
re \cdot im + im \cdot re
\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 3 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: 56.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ re \cdot im + im \cdot re \end{array} \]
(FPCore im_sqr (re im) :precision binary64 (+ (* re im) (* im re)))
double im_sqr(double re, double im) {
	return (re * im) + (im * re);
}
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 im_sqr(re, im)
use fmin_fmax_functions
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    im_sqr = (re * im) + (im * re)
end function
public static double im_sqr(double re, double im) {
	return (re * im) + (im * re);
}
def im_sqr(re, im):
	return (re * im) + (im * re)
function im_sqr(re, im)
	return Float64(Float64(re * im) + Float64(im * re))
end
function tmp = im_sqr(re, im)
	tmp = (re * im) + (im * re);
end
im$95$sqr[re_, im_] := N[(N[(re * im), $MachinePrecision] + N[(im * re), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
re \cdot im + im \cdot re
\end{array}

Alternative 1: 56.4% accurate, 1.4× speedup?

\[\begin{array}{l} re_m = \left|re\right| \\ im_m = \left|im\right| \\ 2 \cdot \left(im\_m \cdot re\_m\right) \end{array} \]
re_m = (fabs.f64 re)
im_m = (fabs.f64 im)
(FPCore im_sqr (re_m im_m) :precision binary64 (* 2.0 (* im_m re_m)))
re_m = fabs(re);
im_m = fabs(im);
double im_sqr(double re_m, double im_m) {
	return 2.0 * (im_m * re_m);
}
re_m =     private
im_m =     private
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 im_sqr(re_m, im_m)
use fmin_fmax_functions
    real(8), intent (in) :: re_m
    real(8), intent (in) :: im_m
    im_sqr = 2.0d0 * (im_m * re_m)
end function
re_m = Math.abs(re);
im_m = Math.abs(im);
public static double im_sqr(double re_m, double im_m) {
	return 2.0 * (im_m * re_m);
}
re_m = math.fabs(re)
im_m = math.fabs(im)
def im_sqr(re_m, im_m):
	return 2.0 * (im_m * re_m)
re_m = abs(re)
im_m = abs(im)
function im_sqr(re_m, im_m)
	return Float64(2.0 * Float64(im_m * re_m))
end
re_m = abs(re);
im_m = abs(im);
function tmp = im_sqr(re_m, im_m)
	tmp = 2.0 * (im_m * re_m);
end
re_m = N[Abs[re], $MachinePrecision]
im_m = N[Abs[im], $MachinePrecision]
im$95$sqr[re$95$m_, im$95$m_] := N[(2.0 * N[(im$95$m * re$95$m), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
re_m = \left|re\right|
\\
im_m = \left|im\right|

\\
2 \cdot \left(im\_m \cdot re\_m\right)
\end{array}
Derivation
  1. Initial program 56.4%

    \[re \cdot im + im \cdot re \]
  2. Taylor expanded in re around 0

    \[\leadsto \color{blue}{2 \cdot \left(im \cdot re\right)} \]
  3. Applied rewrites56.4%

    \[\leadsto \color{blue}{2 \cdot \left(im \cdot re\right)} \]
  4. Add Preprocessing

Alternative 2: 26.1% accurate, 2.4× speedup?

\[\begin{array}{l} re_m = \left|re\right| \\ im_m = \left|im\right| \\ im\_m \cdot re\_m \end{array} \]
re_m = (fabs.f64 re)
im_m = (fabs.f64 im)
(FPCore im_sqr (re_m im_m) :precision binary64 (* im_m re_m))
re_m = fabs(re);
im_m = fabs(im);
double im_sqr(double re_m, double im_m) {
	return im_m * re_m;
}
re_m =     private
im_m =     private
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 im_sqr(re_m, im_m)
use fmin_fmax_functions
    real(8), intent (in) :: re_m
    real(8), intent (in) :: im_m
    im_sqr = im_m * re_m
end function
re_m = Math.abs(re);
im_m = Math.abs(im);
public static double im_sqr(double re_m, double im_m) {
	return im_m * re_m;
}
re_m = math.fabs(re)
im_m = math.fabs(im)
def im_sqr(re_m, im_m):
	return im_m * re_m
re_m = abs(re)
im_m = abs(im)
function im_sqr(re_m, im_m)
	return Float64(im_m * re_m)
end
re_m = abs(re);
im_m = abs(im);
function tmp = im_sqr(re_m, im_m)
	tmp = im_m * re_m;
end
re_m = N[Abs[re], $MachinePrecision]
im_m = N[Abs[im], $MachinePrecision]
im$95$sqr[re$95$m_, im$95$m_] := N[(im$95$m * re$95$m), $MachinePrecision]
\begin{array}{l}
re_m = \left|re\right|
\\
im_m = \left|im\right|

\\
im\_m \cdot re\_m
\end{array}
Derivation
  1. Initial program 56.4%

    \[re \cdot im + im \cdot re \]
  2. Taylor expanded in re around 0

    \[\leadsto \color{blue}{2 \cdot \left(im \cdot re\right)} \]
  3. Applied rewrites56.4%

    \[\leadsto \color{blue}{2 \cdot \left(im \cdot re\right)} \]
  4. Applied rewrites26.1%

    \[\leadsto im \cdot \color{blue}{re} \]
  5. Add Preprocessing

Alternative 3: 14.9% accurate, 9.6× speedup?

\[\begin{array}{l} re_m = \left|re\right| \\ im_m = \left|im\right| \\ 0 \end{array} \]
re_m = (fabs.f64 re)
im_m = (fabs.f64 im)
(FPCore im_sqr (re_m im_m) :precision binary64 0.0)
re_m = fabs(re);
im_m = fabs(im);
double im_sqr(double re_m, double im_m) {
	return 0.0;
}
re_m =     private
im_m =     private
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 im_sqr(re_m, im_m)
use fmin_fmax_functions
    real(8), intent (in) :: re_m
    real(8), intent (in) :: im_m
    im_sqr = 0.0d0
end function
re_m = Math.abs(re);
im_m = Math.abs(im);
public static double im_sqr(double re_m, double im_m) {
	return 0.0;
}
re_m = math.fabs(re)
im_m = math.fabs(im)
def im_sqr(re_m, im_m):
	return 0.0
re_m = abs(re)
im_m = abs(im)
function im_sqr(re_m, im_m)
	return 0.0
end
re_m = abs(re);
im_m = abs(im);
function tmp = im_sqr(re_m, im_m)
	tmp = 0.0;
end
re_m = N[Abs[re], $MachinePrecision]
im_m = N[Abs[im], $MachinePrecision]
im$95$sqr[re$95$m_, im$95$m_] := 0.0
\begin{array}{l}
re_m = \left|re\right|
\\
im_m = \left|im\right|

\\
0
\end{array}
Derivation
  1. Initial program 56.4%

    \[re \cdot im + im \cdot re \]
  2. Applied rewrites14.9%

    \[\leadsto \color{blue}{0} \]
  3. Add Preprocessing

Reproduce

?
herbie shell --seed 2025159 
(FPCore im_sqr (re im)
  :name "math.square on complex, imaginary part"
  :precision binary64
  (+ (* re im) (* im re)))