Lanczos kernel

Percentage Accurate: 97.9% → 97.9%
Time: 4.0s
Alternatives: 15
Speedup: 1.0×

Specification

?
\[\left(10^{-5} \leq x \land x \leq 1\right) \land \left(1 \leq tau \land tau \leq 5\right)\]
\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(x \cdot \pi\right) \cdot tau\\ \frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* x PI) tau)))
   (* (/ (sin t_1) t_1) (/ (sin (* x PI)) (* x PI)))))
float code(float x, float tau) {
	float t_1 = (x * ((float) M_PI)) * tau;
	return (sinf(t_1) / t_1) * (sinf((x * ((float) M_PI))) / (x * ((float) M_PI)));
}
function code(x, tau)
	t_1 = Float32(Float32(x * Float32(pi)) * tau)
	return Float32(Float32(sin(t_1) / t_1) * Float32(sin(Float32(x * Float32(pi))) / Float32(x * Float32(pi))))
end
function tmp = code(x, tau)
	t_1 = (x * single(pi)) * tau;
	tmp = (sin(t_1) / t_1) * (sin((x * single(pi))) / (x * single(pi)));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(x \cdot \pi\right) \cdot tau\\
\frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi}
\end{array}
\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 15 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: 97.9% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(x \cdot \pi\right) \cdot tau\\ \frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* x PI) tau)))
   (* (/ (sin t_1) t_1) (/ (sin (* x PI)) (* x PI)))))
float code(float x, float tau) {
	float t_1 = (x * ((float) M_PI)) * tau;
	return (sinf(t_1) / t_1) * (sinf((x * ((float) M_PI))) / (x * ((float) M_PI)));
}
function code(x, tau)
	t_1 = Float32(Float32(x * Float32(pi)) * tau)
	return Float32(Float32(sin(t_1) / t_1) * Float32(sin(Float32(x * Float32(pi))) / Float32(x * Float32(pi))))
end
function tmp = code(x, tau)
	t_1 = (x * single(pi)) * tau;
	tmp = (sin(t_1) / t_1) * (sin((x * single(pi))) / (x * single(pi)));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(x \cdot \pi\right) \cdot tau\\
\frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi}
\end{array}
\end{array}

Alternative 1: 97.9% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := x \cdot \left(\pi \cdot tau\right)\\ \frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* x (* PI tau))))
   (* (/ (sin t_1) t_1) (/ (sin (* x PI)) (* x PI)))))
float code(float x, float tau) {
	float t_1 = x * (((float) M_PI) * tau);
	return (sinf(t_1) / t_1) * (sinf((x * ((float) M_PI))) / (x * ((float) M_PI)));
}
function code(x, tau)
	t_1 = Float32(x * Float32(Float32(pi) * tau))
	return Float32(Float32(sin(t_1) / t_1) * Float32(sin(Float32(x * Float32(pi))) / Float32(x * Float32(pi))))
end
function tmp = code(x, tau)
	t_1 = x * (single(pi) * tau);
	tmp = (sin(t_1) / t_1) * (sin((x * single(pi))) / (x * single(pi)));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := x \cdot \left(\pi \cdot tau\right)\\
\frac{\sin t\_1}{t\_1} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi}
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Add Preprocessing

Alternative 2: 97.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(tau \cdot x\right) \cdot \pi\\ \frac{\sin t\_1 \cdot \sin \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* tau x) PI)))
   (/ (* (sin t_1) (sin (* x PI))) (* t_1 (* x PI)))))
float code(float x, float tau) {
	float t_1 = (tau * x) * ((float) M_PI);
	return (sinf(t_1) * sinf((x * ((float) M_PI)))) / (t_1 * (x * ((float) M_PI)));
}
function code(x, tau)
	t_1 = Float32(Float32(tau * x) * Float32(pi))
	return Float32(Float32(sin(t_1) * sin(Float32(x * Float32(pi)))) / Float32(t_1 * Float32(x * Float32(pi))))
end
function tmp = code(x, tau)
	t_1 = (tau * x) * single(pi);
	tmp = (sin(t_1) * sin((x * single(pi)))) / (t_1 * (x * single(pi)));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(tau \cdot x\right) \cdot \pi\\
\frac{\sin t\_1 \cdot \sin \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)}
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(\left(tau \cdot x\right) \cdot \pi\right)}}{x \cdot \left(\pi \cdot tau\right)} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  5. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{\color{blue}{\left(tau \cdot x\right) \cdot \pi}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  6. Applied rewrites97.8%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \sin \left(x \cdot \pi\right)}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)}} \]
  7. Add Preprocessing

Alternative 3: 97.6% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(tau \cdot x\right) \cdot \pi\\ \sin t\_1 \cdot \frac{\sin \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* tau x) PI)))
   (* (sin t_1) (/ (sin (* x PI)) (* t_1 (* x PI))))))
float code(float x, float tau) {
	float t_1 = (tau * x) * ((float) M_PI);
	return sinf(t_1) * (sinf((x * ((float) M_PI))) / (t_1 * (x * ((float) M_PI))));
}
function code(x, tau)
	t_1 = Float32(Float32(tau * x) * Float32(pi))
	return Float32(sin(t_1) * Float32(sin(Float32(x * Float32(pi))) / Float32(t_1 * Float32(x * Float32(pi)))))
end
function tmp = code(x, tau)
	t_1 = (tau * x) * single(pi);
	tmp = sin(t_1) * (sin((x * single(pi))) / (t_1 * (x * single(pi))));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(tau \cdot x\right) \cdot \pi\\
\sin t\_1 \cdot \frac{\sin \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)}
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(\left(tau \cdot x\right) \cdot \pi\right)}}{x \cdot \left(\pi \cdot tau\right)} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  5. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{\color{blue}{\left(tau \cdot x\right) \cdot \pi}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  6. Applied rewrites97.8%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \sin \left(x \cdot \pi\right)}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)}} \]
  7. Applied rewrites97.6%

    \[\leadsto \color{blue}{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)}} \]
  8. Add Preprocessing

Alternative 4: 85.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(x \cdot \pi\right) \cdot tau\\ \frac{\sin t\_1}{t\_1} \cdot \left(1 + \left(\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666\right) \cdot \left(-x\right)\right) \cdot \left(-x\right)\right) \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* x PI) tau)))
   (*
    (/ (sin t_1) t_1)
    (+ 1.0 (* (* (* (* PI PI) -0.16666666666666666) (- x)) (- x))))))
float code(float x, float tau) {
	float t_1 = (x * ((float) M_PI)) * tau;
	return (sinf(t_1) / t_1) * (1.0f + ((((((float) M_PI) * ((float) M_PI)) * -0.16666666666666666f) * -x) * -x));
}
function code(x, tau)
	t_1 = Float32(Float32(x * Float32(pi)) * tau)
	return Float32(Float32(sin(t_1) / t_1) * Float32(Float32(1.0) + Float32(Float32(Float32(Float32(Float32(pi) * Float32(pi)) * Float32(-0.16666666666666666)) * Float32(-x)) * Float32(-x))))
end
function tmp = code(x, tau)
	t_1 = (x * single(pi)) * tau;
	tmp = (sin(t_1) / t_1) * (single(1.0) + ((((single(pi) * single(pi)) * single(-0.16666666666666666)) * -x) * -x));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(x \cdot \pi\right) \cdot tau\\
\frac{\sin t\_1}{t\_1} \cdot \left(1 + \left(\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666\right) \cdot \left(-x\right)\right) \cdot \left(-x\right)\right)
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + \frac{-1}{6} \cdot \left({x}^{2} \cdot {\mathsf{PI}\left(\right)}^{2}\right)\right)} \]
  3. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + -0.16666666666666666 \cdot \left({x}^{2} \cdot {\pi}^{2}\right)\right)} \]
  4. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \left(1 + \left(\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666\right) \cdot \left(-x\right)\right) \cdot \color{blue}{\left(-x\right)}\right) \]
  5. Add Preprocessing

Alternative 5: 85.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(x \cdot \pi\right) \cdot tau\\ \frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\pi, \left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right), 1\right) \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* x PI) tau)))
   (* (/ (sin t_1) t_1) (fma PI (* (* -0.16666666666666666 PI) (* x x)) 1.0))))
float code(float x, float tau) {
	float t_1 = (x * ((float) M_PI)) * tau;
	return (sinf(t_1) / t_1) * fmaf(((float) M_PI), ((-0.16666666666666666f * ((float) M_PI)) * (x * x)), 1.0f);
}
function code(x, tau)
	t_1 = Float32(Float32(x * Float32(pi)) * tau)
	return Float32(Float32(sin(t_1) / t_1) * fma(Float32(pi), Float32(Float32(Float32(-0.16666666666666666) * Float32(pi)) * Float32(x * x)), Float32(1.0)))
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(x \cdot \pi\right) \cdot tau\\
\frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\pi, \left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right), 1\right)
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + \frac{-1}{6} \cdot \left({x}^{2} \cdot {\mathsf{PI}\left(\right)}^{2}\right)\right)} \]
  3. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + -0.16666666666666666 \cdot \left({x}^{2} \cdot {\pi}^{2}\right)\right)} \]
  4. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \mathsf{fma}\left(\pi, \color{blue}{\left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right)}, 1\right) \]
  5. Add Preprocessing

Alternative 6: 85.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(tau \cdot x\right) \cdot \pi\\ \frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\pi, \left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right), 1\right) \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* tau x) PI)))
   (* (/ (sin t_1) t_1) (fma PI (* (* -0.16666666666666666 PI) (* x x)) 1.0))))
float code(float x, float tau) {
	float t_1 = (tau * x) * ((float) M_PI);
	return (sinf(t_1) / t_1) * fmaf(((float) M_PI), ((-0.16666666666666666f * ((float) M_PI)) * (x * x)), 1.0f);
}
function code(x, tau)
	t_1 = Float32(Float32(tau * x) * Float32(pi))
	return Float32(Float32(sin(t_1) / t_1) * fma(Float32(pi), Float32(Float32(Float32(-0.16666666666666666) * Float32(pi)) * Float32(x * x)), Float32(1.0)))
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(tau \cdot x\right) \cdot \pi\\
\frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\pi, \left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right), 1\right)
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + \frac{-1}{6} \cdot \left({x}^{2} \cdot {\mathsf{PI}\left(\right)}^{2}\right)\right)} \]
  3. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + -0.16666666666666666 \cdot \left({x}^{2} \cdot {\pi}^{2}\right)\right)} \]
  4. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \mathsf{fma}\left(\pi, \color{blue}{\left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right)}, 1\right) \]
  5. Applied rewrites85.1%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{\left(tau \cdot x\right) \cdot \pi} \cdot \mathsf{fma}\left(\pi, \left(-0.16666666666666666 \cdot \pi\right) \cdot \left(x \cdot x\right), 1\right)} \]
  6. Add Preprocessing

Alternative 7: 85.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := x \cdot \left(\pi \cdot tau\right)\\ \frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666, x \cdot x, 1\right) \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* x (* PI tau))))
   (* (/ (sin t_1) t_1) (fma (* (* PI PI) -0.16666666666666666) (* x x) 1.0))))
float code(float x, float tau) {
	float t_1 = x * (((float) M_PI) * tau);
	return (sinf(t_1) / t_1) * fmaf(((((float) M_PI) * ((float) M_PI)) * -0.16666666666666666f), (x * x), 1.0f);
}
function code(x, tau)
	t_1 = Float32(x * Float32(Float32(pi) * tau))
	return Float32(Float32(sin(t_1) / t_1) * fma(Float32(Float32(Float32(pi) * Float32(pi)) * Float32(-0.16666666666666666)), Float32(x * x), Float32(1.0)))
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := x \cdot \left(\pi \cdot tau\right)\\
\frac{\sin t\_1}{t\_1} \cdot \mathsf{fma}\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666, x \cdot x, 1\right)
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + \frac{-1}{6} \cdot \left({x}^{2} \cdot {\mathsf{PI}\left(\right)}^{2}\right)\right)} \]
  3. Applied rewrites85.1%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\left(1 + -0.16666666666666666 \cdot \left({x}^{2} \cdot {\pi}^{2}\right)\right)} \]
  4. Applied rewrites85.1%

    \[\leadsto \color{blue}{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{x \cdot \left(\pi \cdot tau\right)} \cdot \mathsf{fma}\left(\left(\pi \cdot \pi\right) \cdot -0.16666666666666666, x \cdot x, 1\right)} \]
  5. Add Preprocessing

Alternative 8: 70.9% accurate, 1.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(tau \cdot x\right) \cdot \pi\\ \frac{\sin t\_1 \cdot \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* tau x) PI))) (/ (* (sin t_1) (* x PI)) (* t_1 (* x PI)))))
float code(float x, float tau) {
	float t_1 = (tau * x) * ((float) M_PI);
	return (sinf(t_1) * (x * ((float) M_PI))) / (t_1 * (x * ((float) M_PI)));
}
function code(x, tau)
	t_1 = Float32(Float32(tau * x) * Float32(pi))
	return Float32(Float32(sin(t_1) * Float32(x * Float32(pi))) / Float32(t_1 * Float32(x * Float32(pi))))
end
function tmp = code(x, tau)
	t_1 = (tau * x) * single(pi);
	tmp = (sin(t_1) * (x * single(pi))) / (t_1 * (x * single(pi)));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(tau \cdot x\right) \cdot \pi\\
\frac{\sin t\_1 \cdot \left(x \cdot \pi\right)}{t\_1 \cdot \left(x \cdot \pi\right)}
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(\left(tau \cdot x\right) \cdot \pi\right)}}{x \cdot \left(\pi \cdot tau\right)} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  5. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{\color{blue}{\left(tau \cdot x\right) \cdot \pi}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  6. Applied rewrites97.8%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \sin \left(x \cdot \pi\right)}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)}} \]
  7. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \color{blue}{\left(x \cdot \mathsf{PI}\left(\right)\right)}}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)} \]
  8. Applied rewrites70.9%

    \[\leadsto \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \color{blue}{\left(x \cdot \pi\right)}}{\left(\left(tau \cdot x\right) \cdot \pi\right) \cdot \left(x \cdot \pi\right)} \]
  9. Add Preprocessing

Alternative 9: 70.9% accurate, 1.7× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \left(tau \cdot x\right) \cdot \pi\\ \frac{\sin t\_1}{t\_1} \cdot \frac{\pi}{\pi} \end{array} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (let* ((t_1 (* (* tau x) PI))) (* (/ (sin t_1) t_1) (/ PI PI))))
float code(float x, float tau) {
	float t_1 = (tau * x) * ((float) M_PI);
	return (sinf(t_1) / t_1) * (((float) M_PI) / ((float) M_PI));
}
function code(x, tau)
	t_1 = Float32(Float32(tau * x) * Float32(pi))
	return Float32(Float32(sin(t_1) / t_1) * Float32(Float32(pi) / Float32(pi)))
end
function tmp = code(x, tau)
	t_1 = (tau * x) * single(pi);
	tmp = (sin(t_1) / t_1) * (single(pi) / single(pi));
end
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \left(tau \cdot x\right) \cdot \pi\\
\frac{\sin t\_1}{t\_1} \cdot \frac{\pi}{\pi}
\end{array}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.6%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \color{blue}{\frac{\frac{\sin \left(x \cdot \pi\right)}{x}}{\pi}} \]
  3. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\color{blue}{\mathsf{PI}\left(\right)}}{\pi} \]
  4. Applied rewrites70.9%

    \[\leadsto \frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\color{blue}{\pi}}{\pi} \]
  5. Applied rewrites70.9%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{\left(tau \cdot x\right) \cdot \pi} \cdot \frac{\pi}{\pi}} \]
  6. Add Preprocessing

Alternative 10: 70.9% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \frac{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau}}{x} \cdot \frac{1}{\pi} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (* (/ (/ (sin (* (* tau x) PI)) tau) x) (/ 1.0 PI)))
float code(float x, float tau) {
	return ((sinf(((tau * x) * ((float) M_PI))) / tau) / x) * (1.0f / ((float) M_PI));
}
function code(x, tau)
	return Float32(Float32(Float32(sin(Float32(Float32(tau * x) * Float32(pi))) / tau) / x) * Float32(Float32(1.0) / Float32(pi)))
end
function tmp = code(x, tau)
	tmp = ((sin(((tau * x) * single(pi))) / tau) / x) * (single(1.0) / single(pi));
end
\begin{array}{l}

\\
\frac{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau}}{x} \cdot \frac{1}{\pi}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.0%

    \[\leadsto \color{blue}{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(\pi \cdot \pi\right) \cdot x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \]
  6. Applied rewrites70.7%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\pi}} \]
  7. Applied rewrites70.7%

    \[\leadsto \color{blue}{\frac{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau}}{x}} \cdot \frac{1}{\pi} \]
  8. Add Preprocessing

Alternative 11: 70.7% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau \cdot x} \cdot \frac{1}{\pi} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (* (/ (sin (* (* tau x) PI)) (* tau x)) (/ 1.0 PI)))
float code(float x, float tau) {
	return (sinf(((tau * x) * ((float) M_PI))) / (tau * x)) * (1.0f / ((float) M_PI));
}
function code(x, tau)
	return Float32(Float32(sin(Float32(Float32(tau * x) * Float32(pi))) / Float32(tau * x)) * Float32(Float32(1.0) / Float32(pi)))
end
function tmp = code(x, tau)
	tmp = (sin(((tau * x) * single(pi))) / (tau * x)) * (single(1.0) / single(pi));
end
\begin{array}{l}

\\
\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau \cdot x} \cdot \frac{1}{\pi}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.0%

    \[\leadsto \color{blue}{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(\pi \cdot \pi\right) \cdot x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \]
  6. Applied rewrites70.7%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\pi}} \]
  7. Applied rewrites70.9%

    \[\leadsto \color{blue}{\frac{\sin \left(\left(tau \cdot x\right) \cdot \pi\right)}{tau \cdot x}} \cdot \frac{1}{\pi} \]
  8. Add Preprocessing

Alternative 12: 70.7% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{1}{\pi} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (* (/ (sin (* x (* PI tau))) (* tau x)) (/ 1.0 PI)))
float code(float x, float tau) {
	return (sinf((x * (((float) M_PI) * tau))) / (tau * x)) * (1.0f / ((float) M_PI));
}
function code(x, tau)
	return Float32(Float32(sin(Float32(x * Float32(Float32(pi) * tau))) / Float32(tau * x)) * Float32(Float32(1.0) / Float32(pi)))
end
function tmp = code(x, tau)
	tmp = (sin((x * (single(pi) * tau))) / (tau * x)) * (single(1.0) / single(pi));
end
\begin{array}{l}

\\
\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{1}{\pi}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.0%

    \[\leadsto \color{blue}{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(\pi \cdot \pi\right) \cdot x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \]
  6. Applied rewrites70.7%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\pi}} \]
  7. Add Preprocessing

Alternative 13: 70.7% accurate, 1.8× speedup?

\[\begin{array}{l} \\ \frac{\sin \left(tau \cdot \left(x \cdot \pi\right)\right)}{tau \cdot x} \cdot \frac{1}{\pi} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (* (/ (sin (* tau (* x PI))) (* tau x)) (/ 1.0 PI)))
float code(float x, float tau) {
	return (sinf((tau * (x * ((float) M_PI)))) / (tau * x)) * (1.0f / ((float) M_PI));
}
function code(x, tau)
	return Float32(Float32(sin(Float32(tau * Float32(x * Float32(pi)))) / Float32(tau * x)) * Float32(Float32(1.0) / Float32(pi)))
end
function tmp = code(x, tau)
	tmp = (sin((tau * (x * single(pi)))) / (tau * x)) * (single(1.0) / single(pi));
end
\begin{array}{l}

\\
\frac{\sin \left(tau \cdot \left(x \cdot \pi\right)\right)}{tau \cdot x} \cdot \frac{1}{\pi}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.0%

    \[\leadsto \color{blue}{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(\pi \cdot \pi\right) \cdot x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\mathsf{PI}\left(\right)}} \]
  6. Applied rewrites70.7%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{tau \cdot x} \cdot \color{blue}{\frac{1}{\pi}} \]
  7. Taylor expanded in x around inf

    \[\leadsto \color{blue}{\frac{\sin \left(tau \cdot \left(x \cdot \mathsf{PI}\left(\right)\right)\right)}{tau \cdot x}} \cdot \frac{1}{\pi} \]
  8. Applied rewrites70.7%

    \[\leadsto \color{blue}{\frac{\sin \left(tau \cdot \left(x \cdot \pi\right)\right)}{tau \cdot x}} \cdot \frac{1}{\pi} \]
  9. Add Preprocessing

Alternative 14: 64.2% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \frac{tau}{\pi} \cdot \frac{\sin \left(x \cdot \pi\right)}{tau \cdot x} \end{array} \]
(FPCore (x tau)
 :precision binary32
 (* (/ tau PI) (/ (sin (* x PI)) (* tau x))))
float code(float x, float tau) {
	return (tau / ((float) M_PI)) * (sinf((x * ((float) M_PI))) / (tau * x));
}
function code(x, tau)
	return Float32(Float32(tau / Float32(pi)) * Float32(sin(Float32(x * Float32(pi))) / Float32(tau * x)))
end
function tmp = code(x, tau)
	tmp = (tau / single(pi)) * (sin((x * single(pi))) / (tau * x));
end
\begin{array}{l}

\\
\frac{tau}{\pi} \cdot \frac{\sin \left(x \cdot \pi\right)}{tau \cdot x}
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Applied rewrites97.3%

    \[\leadsto \frac{\sin \color{blue}{\left(x \cdot \left(\pi \cdot tau\right)\right)}}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  3. Applied rewrites97.9%

    \[\leadsto \frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{\color{blue}{x \cdot \left(\pi \cdot tau\right)}} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  4. Applied rewrites97.1%

    \[\leadsto \color{blue}{\frac{\frac{\sin \left(x \cdot \left(\pi \cdot tau\right)\right)}{x \cdot \pi}}{\pi} \cdot \frac{\sin \left(x \cdot \pi\right)}{tau \cdot x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{\color{blue}{tau}}{\pi} \cdot \frac{\sin \left(x \cdot \pi\right)}{tau \cdot x} \]
  6. Applied rewrites64.2%

    \[\leadsto \frac{\color{blue}{tau}}{\pi} \cdot \frac{\sin \left(x \cdot \pi\right)}{tau \cdot x} \]
  7. Add Preprocessing

Alternative 15: 63.5% accurate, 94.3× speedup?

\[\begin{array}{l} \\ 1 \end{array} \]
(FPCore (x tau) :precision binary32 1.0)
float code(float x, float tau) {
	return 1.0f;
}
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(4) function code(x, tau)
use fmin_fmax_functions
    real(4), intent (in) :: x
    real(4), intent (in) :: tau
    code = 1.0e0
end function
function code(x, tau)
	return Float32(1.0)
end
function tmp = code(x, tau)
	tmp = single(1.0);
end
\begin{array}{l}

\\
1
\end{array}
Derivation
  1. Initial program 97.9%

    \[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]
  2. Taylor expanded in x around 0

    \[\leadsto \color{blue}{1} \]
  3. Applied rewrites63.5%

    \[\leadsto \color{blue}{1} \]
  4. Add Preprocessing

Reproduce

?
herbie shell --seed 2025161 
(FPCore (x tau)
  :name "Lanczos kernel"
  :precision binary32
  :pre (and (and (<= 1e-5 x) (<= x 1.0)) (and (<= 1.0 tau) (<= tau 5.0)))
  (* (/ (sin (* (* x PI) tau)) (* (* x PI) tau)) (/ (sin (* x PI)) (* x PI))))