Codec.Picture.Jpg.FastDct:referenceDct from JuicyPixels-3.2.6.1

Percentage Accurate: 27.9% → 30.7%
Time: 25.7s
Alternatives: 2
Speedup: 225.0×

Specification

?
\[\begin{array}{l} \\ \left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right) \end{array} \]
(FPCore (x y z t a b)
 :precision binary64
 (*
  (* x (cos (/ (* (* (+ (* y 2.0) 1.0) z) t) 16.0)))
  (cos (/ (* (* (+ (* a 2.0) 1.0) b) t) 16.0))))
double code(double x, double y, double z, double t, double a, double b) {
	return (x * cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
}
real(8) function code(x, y, z, t, a, b)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = (x * cos((((((y * 2.0d0) + 1.0d0) * z) * t) / 16.0d0))) * cos((((((a * 2.0d0) + 1.0d0) * b) * t) / 16.0d0))
end function
public static double code(double x, double y, double z, double t, double a, double b) {
	return (x * Math.cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * Math.cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
}
def code(x, y, z, t, a, b):
	return (x * math.cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * math.cos((((((a * 2.0) + 1.0) * b) * t) / 16.0))
function code(x, y, z, t, a, b)
	return Float64(Float64(x * cos(Float64(Float64(Float64(Float64(Float64(y * 2.0) + 1.0) * z) * t) / 16.0))) * cos(Float64(Float64(Float64(Float64(Float64(a * 2.0) + 1.0) * b) * t) / 16.0)))
end
function tmp = code(x, y, z, t, a, b)
	tmp = (x * cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
end
code[x_, y_, z_, t_, a_, b_] := N[(N[(x * N[Cos[N[(N[(N[(N[(N[(y * 2.0), $MachinePrecision] + 1.0), $MachinePrecision] * z), $MachinePrecision] * t), $MachinePrecision] / 16.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[Cos[N[(N[(N[(N[(N[(a * 2.0), $MachinePrecision] + 1.0), $MachinePrecision] * b), $MachinePrecision] * t), $MachinePrecision] / 16.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right)
\end{array}

Sampling outcomes in binary64 precision:

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 2 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: 27.9% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right) \end{array} \]
(FPCore (x y z t a b)
 :precision binary64
 (*
  (* x (cos (/ (* (* (+ (* y 2.0) 1.0) z) t) 16.0)))
  (cos (/ (* (* (+ (* a 2.0) 1.0) b) t) 16.0))))
double code(double x, double y, double z, double t, double a, double b) {
	return (x * cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
}
real(8) function code(x, y, z, t, a, b)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = (x * cos((((((y * 2.0d0) + 1.0d0) * z) * t) / 16.0d0))) * cos((((((a * 2.0d0) + 1.0d0) * b) * t) / 16.0d0))
end function
public static double code(double x, double y, double z, double t, double a, double b) {
	return (x * Math.cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * Math.cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
}
def code(x, y, z, t, a, b):
	return (x * math.cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * math.cos((((((a * 2.0) + 1.0) * b) * t) / 16.0))
function code(x, y, z, t, a, b)
	return Float64(Float64(x * cos(Float64(Float64(Float64(Float64(Float64(y * 2.0) + 1.0) * z) * t) / 16.0))) * cos(Float64(Float64(Float64(Float64(Float64(a * 2.0) + 1.0) * b) * t) / 16.0)))
end
function tmp = code(x, y, z, t, a, b)
	tmp = (x * cos((((((y * 2.0) + 1.0) * z) * t) / 16.0))) * cos((((((a * 2.0) + 1.0) * b) * t) / 16.0));
end
code[x_, y_, z_, t_, a_, b_] := N[(N[(x * N[Cos[N[(N[(N[(N[(N[(y * 2.0), $MachinePrecision] + 1.0), $MachinePrecision] * z), $MachinePrecision] * t), $MachinePrecision] / 16.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[Cos[N[(N[(N[(N[(N[(a * 2.0), $MachinePrecision] + 1.0), $MachinePrecision] * b), $MachinePrecision] * t), $MachinePrecision] / 16.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right)
\end{array}

Alternative 1: 30.7% accurate, 0.7× speedup?

\[\begin{array}{l} z_m = \left|z\right| \\ x \cdot \cos \left(\left(e^{z\_m \cdot \left(1 + \left(2 \cdot y + -0.5 \cdot \left(z\_m \cdot {\left(1 + 2 \cdot y\right)}^{2}\right)\right)\right)} + -1\right) \cdot \frac{t}{16}\right) \end{array} \]
z_m = (fabs.f64 z)
(FPCore (x y z_m t a b)
 :precision binary64
 (*
  x
  (cos
   (*
    (+
     (exp
      (*
       z_m
       (+ 1.0 (+ (* 2.0 y) (* -0.5 (* z_m (pow (+ 1.0 (* 2.0 y)) 2.0)))))))
     -1.0)
    (/ t 16.0)))))
z_m = fabs(z);
double code(double x, double y, double z_m, double t, double a, double b) {
	return x * cos(((exp((z_m * (1.0 + ((2.0 * y) + (-0.5 * (z_m * pow((1.0 + (2.0 * y)), 2.0))))))) + -1.0) * (t / 16.0)));
}
z_m = abs(z)
real(8) function code(x, y, z_m, t, a, b)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z_m
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = x * cos(((exp((z_m * (1.0d0 + ((2.0d0 * y) + ((-0.5d0) * (z_m * ((1.0d0 + (2.0d0 * y)) ** 2.0d0))))))) + (-1.0d0)) * (t / 16.0d0)))
end function
z_m = Math.abs(z);
public static double code(double x, double y, double z_m, double t, double a, double b) {
	return x * Math.cos(((Math.exp((z_m * (1.0 + ((2.0 * y) + (-0.5 * (z_m * Math.pow((1.0 + (2.0 * y)), 2.0))))))) + -1.0) * (t / 16.0)));
}
z_m = math.fabs(z)
def code(x, y, z_m, t, a, b):
	return x * math.cos(((math.exp((z_m * (1.0 + ((2.0 * y) + (-0.5 * (z_m * math.pow((1.0 + (2.0 * y)), 2.0))))))) + -1.0) * (t / 16.0)))
z_m = abs(z)
function code(x, y, z_m, t, a, b)
	return Float64(x * cos(Float64(Float64(exp(Float64(z_m * Float64(1.0 + Float64(Float64(2.0 * y) + Float64(-0.5 * Float64(z_m * (Float64(1.0 + Float64(2.0 * y)) ^ 2.0))))))) + -1.0) * Float64(t / 16.0))))
end
z_m = abs(z);
function tmp = code(x, y, z_m, t, a, b)
	tmp = x * cos(((exp((z_m * (1.0 + ((2.0 * y) + (-0.5 * (z_m * ((1.0 + (2.0 * y)) ^ 2.0))))))) + -1.0) * (t / 16.0)));
end
z_m = N[Abs[z], $MachinePrecision]
code[x_, y_, z$95$m_, t_, a_, b_] := N[(x * N[Cos[N[(N[(N[Exp[N[(z$95$m * N[(1.0 + N[(N[(2.0 * y), $MachinePrecision] + N[(-0.5 * N[(z$95$m * N[Power[N[(1.0 + N[(2.0 * y), $MachinePrecision]), $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + -1.0), $MachinePrecision] * N[(t / 16.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
z_m = \left|z\right|

\\
x \cdot \cos \left(\left(e^{z\_m \cdot \left(1 + \left(2 \cdot y + -0.5 \cdot \left(z\_m \cdot {\left(1 + 2 \cdot y\right)}^{2}\right)\right)\right)} + -1\right) \cdot \frac{t}{16}\right)
\end{array}
Derivation
  1. Initial program 24.5%

    \[\left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right) \]
  2. Simplified24.5%

    \[\leadsto \color{blue}{x \cdot \left(\cos \left(\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right) \cdot \frac{t}{16}\right) \cdot \cos \left(\left(\mathsf{fma}\left(a, 2, 1\right) \cdot b\right) \cdot \frac{t}{16}\right)\right)} \]
  3. Add Preprocessing
  4. Taylor expanded in b around 0 26.8%

    \[\leadsto x \cdot \left(\cos \left(\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right) \cdot \frac{t}{16}\right) \cdot \color{blue}{1}\right) \]
  5. Step-by-step derivation
    1. expm1-log1p-u22.1%

      \[\leadsto x \cdot \left(\cos \left(\color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right)\right)} \cdot \frac{t}{16}\right) \cdot 1\right) \]
    2. expm1-undefine22.1%

      \[\leadsto x \cdot \left(\cos \left(\color{blue}{\left(e^{\mathsf{log1p}\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right)} - 1\right)} \cdot \frac{t}{16}\right) \cdot 1\right) \]
  6. Applied egg-rr22.1%

    \[\leadsto x \cdot \left(\cos \left(\color{blue}{\left(e^{\mathsf{log1p}\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right)} - 1\right)} \cdot \frac{t}{16}\right) \cdot 1\right) \]
  7. Taylor expanded in z around 0 28.8%

    \[\leadsto x \cdot \left(\cos \left(\left(e^{\color{blue}{z \cdot \left(1 + \left(-0.5 \cdot \left(z \cdot {\left(1 + 2 \cdot y\right)}^{2}\right) + 2 \cdot y\right)\right)}} - 1\right) \cdot \frac{t}{16}\right) \cdot 1\right) \]
  8. Final simplification28.8%

    \[\leadsto x \cdot \cos \left(\left(e^{z \cdot \left(1 + \left(2 \cdot y + -0.5 \cdot \left(z \cdot {\left(1 + 2 \cdot y\right)}^{2}\right)\right)\right)} + -1\right) \cdot \frac{t}{16}\right) \]
  9. Add Preprocessing

Alternative 2: 30.8% accurate, 225.0× speedup?

\[\begin{array}{l} z_m = \left|z\right| \\ x \end{array} \]
z_m = (fabs.f64 z)
(FPCore (x y z_m t a b) :precision binary64 x)
z_m = fabs(z);
double code(double x, double y, double z_m, double t, double a, double b) {
	return x;
}
z_m = abs(z)
real(8) function code(x, y, z_m, t, a, b)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z_m
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = x
end function
z_m = Math.abs(z);
public static double code(double x, double y, double z_m, double t, double a, double b) {
	return x;
}
z_m = math.fabs(z)
def code(x, y, z_m, t, a, b):
	return x
z_m = abs(z)
function code(x, y, z_m, t, a, b)
	return x
end
z_m = abs(z);
function tmp = code(x, y, z_m, t, a, b)
	tmp = x;
end
z_m = N[Abs[z], $MachinePrecision]
code[x_, y_, z$95$m_, t_, a_, b_] := x
\begin{array}{l}
z_m = \left|z\right|

\\
x
\end{array}
Derivation
  1. Initial program 24.5%

    \[\left(x \cdot \cos \left(\frac{\left(\left(y \cdot 2 + 1\right) \cdot z\right) \cdot t}{16}\right)\right) \cdot \cos \left(\frac{\left(\left(a \cdot 2 + 1\right) \cdot b\right) \cdot t}{16}\right) \]
  2. Simplified24.5%

    \[\leadsto \color{blue}{x \cdot \left(\cos \left(\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right) \cdot \frac{t}{16}\right) \cdot \cos \left(\left(\mathsf{fma}\left(a, 2, 1\right) \cdot b\right) \cdot \frac{t}{16}\right)\right)} \]
  3. Add Preprocessing
  4. Taylor expanded in b around 0 26.8%

    \[\leadsto x \cdot \left(\cos \left(\left(\mathsf{fma}\left(y, 2, 1\right) \cdot z\right) \cdot \frac{t}{16}\right) \cdot \color{blue}{1}\right) \]
  5. Taylor expanded in z around 0 28.2%

    \[\leadsto \color{blue}{x} \]
  6. Final simplification28.2%

    \[\leadsto x \]
  7. Add Preprocessing

Developer target: 30.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ x \cdot \cos \left(\frac{b}{16} \cdot \frac{t}{\left(1 - a \cdot 2\right) + {\left(a \cdot 2\right)}^{2}}\right) \end{array} \]
(FPCore (x y z t a b)
 :precision binary64
 (* x (cos (* (/ b 16.0) (/ t (+ (- 1.0 (* a 2.0)) (pow (* a 2.0) 2.0)))))))
double code(double x, double y, double z, double t, double a, double b) {
	return x * cos(((b / 16.0) * (t / ((1.0 - (a * 2.0)) + pow((a * 2.0), 2.0)))));
}
real(8) function code(x, y, z, t, a, b)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = x * cos(((b / 16.0d0) * (t / ((1.0d0 - (a * 2.0d0)) + ((a * 2.0d0) ** 2.0d0)))))
end function
public static double code(double x, double y, double z, double t, double a, double b) {
	return x * Math.cos(((b / 16.0) * (t / ((1.0 - (a * 2.0)) + Math.pow((a * 2.0), 2.0)))));
}
def code(x, y, z, t, a, b):
	return x * math.cos(((b / 16.0) * (t / ((1.0 - (a * 2.0)) + math.pow((a * 2.0), 2.0)))))
function code(x, y, z, t, a, b)
	return Float64(x * cos(Float64(Float64(b / 16.0) * Float64(t / Float64(Float64(1.0 - Float64(a * 2.0)) + (Float64(a * 2.0) ^ 2.0))))))
end
function tmp = code(x, y, z, t, a, b)
	tmp = x * cos(((b / 16.0) * (t / ((1.0 - (a * 2.0)) + ((a * 2.0) ^ 2.0)))));
end
code[x_, y_, z_, t_, a_, b_] := N[(x * N[Cos[N[(N[(b / 16.0), $MachinePrecision] * N[(t / N[(N[(1.0 - N[(a * 2.0), $MachinePrecision]), $MachinePrecision] + N[Power[N[(a * 2.0), $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x \cdot \cos \left(\frac{b}{16} \cdot \frac{t}{\left(1 - a \cdot 2\right) + {\left(a \cdot 2\right)}^{2}}\right)
\end{array}

Reproduce

?
herbie shell --seed 2024130 
(FPCore (x y z t a b)
  :name "Codec.Picture.Jpg.FastDct:referenceDct from JuicyPixels-3.2.6.1"
  :precision binary64

  :alt
  (* x (cos (* (/ b 16.0) (/ t (+ (- 1.0 (* a 2.0)) (pow (* a 2.0) 2.0))))))

  (* (* x (cos (/ (* (* (+ (* y 2.0) 1.0) z) t) 16.0))) (cos (/ (* (* (+ (* a 2.0) 1.0) b) t) 16.0))))