
(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}
Sampling outcomes in binary32 precision:
Herbie found 15 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(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}
(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}
Initial program 98.1%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* x (* PI tau)))) (* (sin t_1) (/ (sin (* x PI)) (* (* x PI) t_1)))))
float code(float x, float tau) {
float t_1 = x * (((float) M_PI) * tau);
return sinf(t_1) * (sinf((x * ((float) M_PI))) / ((x * ((float) M_PI)) * t_1));
}
function code(x, tau) t_1 = Float32(x * Float32(Float32(pi) * tau)) return Float32(sin(t_1) * Float32(sin(Float32(x * Float32(pi))) / Float32(Float32(x * Float32(pi)) * t_1))) end
function tmp = code(x, tau) t_1 = x * (single(pi) * tau); tmp = sin(t_1) * (sin((x * single(pi))) / ((x * single(pi)) * t_1)); end
\begin{array}{l}
\\
\begin{array}{l}
t_1 := x \cdot \left(\pi \cdot tau\right)\\
\sin t\_1 \cdot \frac{\sin \left(x \cdot \pi\right)}{\left(x \cdot \pi\right) \cdot t\_1}
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around inf
associate-/l*N/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
associate-*r*N/A
unpow2N/A
associate-*r*N/A
associate-/r*N/A
associate-/l/N/A
lower-/.f32N/A
Applied rewrites96.7%
Applied rewrites97.7%
Final simplification97.7%
(FPCore (x tau) :precision binary32 (* (sin (* x (* PI tau))) (/ (sin (* x PI)) (* PI (* (* PI tau) (* x x))))))
float code(float x, float tau) {
return sinf((x * (((float) M_PI) * tau))) * (sinf((x * ((float) M_PI))) / (((float) M_PI) * ((((float) M_PI) * tau) * (x * x))));
}
function code(x, tau) return Float32(sin(Float32(x * Float32(Float32(pi) * tau))) * Float32(sin(Float32(x * Float32(pi))) / Float32(Float32(pi) * Float32(Float32(Float32(pi) * tau) * Float32(x * x))))) end
function tmp = code(x, tau) tmp = sin((x * (single(pi) * tau))) * (sin((x * single(pi))) / (single(pi) * ((single(pi) * tau) * (x * x)))); end
\begin{array}{l}
\\
\sin \left(x \cdot \left(\pi \cdot tau\right)\right) \cdot \frac{\sin \left(x \cdot \pi\right)}{\pi \cdot \left(\left(\pi \cdot tau\right) \cdot \left(x \cdot x\right)\right)}
\end{array}
Initial program 98.1%
Taylor expanded in x around inf
associate-/l*N/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
associate-*r*N/A
*-commutativeN/A
lower-*.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
associate-*r*N/A
unpow2N/A
associate-*r*N/A
associate-/r*N/A
associate-/l/N/A
lower-/.f32N/A
Applied rewrites96.7%
Applied rewrites97.1%
Final simplification97.1%
(FPCore (x tau)
:precision binary32
(*
(/ (sin (* PI (* x tau))) tau)
(/
(fma
(* x x)
(*
PI
(fma (* (* x x) 0.008333333333333333) (* PI PI) -0.16666666666666666))
(/ 1.0 PI))
x)))
float code(float x, float tau) {
return (sinf((((float) M_PI) * (x * tau))) / tau) * (fmaf((x * x), (((float) M_PI) * fmaf(((x * x) * 0.008333333333333333f), (((float) M_PI) * ((float) M_PI)), -0.16666666666666666f)), (1.0f / ((float) M_PI))) / x);
}
function code(x, tau) return Float32(Float32(sin(Float32(Float32(pi) * Float32(x * tau))) / tau) * Float32(fma(Float32(x * x), Float32(Float32(pi) * fma(Float32(Float32(x * x) * Float32(0.008333333333333333)), Float32(Float32(pi) * Float32(pi)), Float32(-0.16666666666666666))), Float32(Float32(1.0) / Float32(pi))) / x)) end
\begin{array}{l}
\\
\frac{\sin \left(\pi \cdot \left(x \cdot tau\right)\right)}{tau} \cdot \frac{\mathsf{fma}\left(x \cdot x, \pi \cdot \mathsf{fma}\left(\left(x \cdot x\right) \cdot 0.008333333333333333, \pi \cdot \pi, -0.16666666666666666\right), \frac{1}{\pi}\right)}{x}
\end{array}
Initial program 98.1%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-*.f32N/A
*-commutativeN/A
times-fracN/A
lower-*.f32N/A
Applied rewrites97.3%
Taylor expanded in x around 0
lower-/.f32N/A
Applied rewrites91.2%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* (* x PI) tau))) (* (/ (sin t_1) t_1) (fma (* PI PI) (* x (* x -0.16666666666666666)) 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)), (x * (x * -0.16666666666666666f)), 1.0f);
}
function code(x, tau) t_1 = Float32(Float32(x * Float32(pi)) * tau) return Float32(Float32(sin(t_1) / t_1) * fma(Float32(Float32(pi) * Float32(pi)), Float32(x * Float32(x * Float32(-0.16666666666666666))), 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 \cdot \pi, x \cdot \left(x \cdot -0.16666666666666666\right), 1\right)
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Applied rewrites85.6%
Final simplification85.6%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* (* x PI) tau))) (* (/ (sin t_1) t_1) (fma (* x x) (* (* PI PI) -0.16666666666666666) 1.0))))
float code(float x, float tau) {
float t_1 = (x * ((float) M_PI)) * tau;
return (sinf(t_1) / t_1) * fmaf((x * x), ((((float) M_PI) * ((float) M_PI)) * -0.16666666666666666f), 1.0f);
}
function code(x, tau) t_1 = Float32(Float32(x * Float32(pi)) * tau) return Float32(Float32(sin(t_1) / t_1) * fma(Float32(x * x), Float32(Float32(Float32(pi) * Float32(pi)) * Float32(-0.16666666666666666)), 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(x \cdot x, \left(\pi \cdot \pi\right) \cdot -0.16666666666666666, 1\right)
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Taylor expanded in x around 0
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f3285.6
Applied rewrites85.6%
Final simplification85.6%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* x (* PI tau)))) (* (sin t_1) (/ (fma (* PI PI) (* (* x x) -0.16666666666666666) 1.0) t_1))))
float code(float x, float tau) {
float t_1 = x * (((float) M_PI) * tau);
return sinf(t_1) * (fmaf((((float) M_PI) * ((float) M_PI)), ((x * x) * -0.16666666666666666f), 1.0f) / t_1);
}
function code(x, tau) t_1 = Float32(x * Float32(Float32(pi) * tau)) return Float32(sin(t_1) * Float32(fma(Float32(Float32(pi) * Float32(pi)), Float32(Float32(x * x) * Float32(-0.16666666666666666)), Float32(1.0)) / t_1)) end
\begin{array}{l}
\\
\begin{array}{l}
t_1 := x \cdot \left(\pi \cdot tau\right)\\
\sin t\_1 \cdot \frac{\mathsf{fma}\left(\pi \cdot \pi, \left(x \cdot x\right) \cdot -0.16666666666666666, 1\right)}{t\_1}
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
lift-*.f32N/A
lift-/.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*r*N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
lift-*.f32N/A
associate-*r*N/A
lift-*.f32N/A
lift-*.f32N/A
Applied rewrites85.4%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* (* x PI) tau))) (* (sin t_1) (/ (fma (* x -0.16666666666666666) (* x (* PI PI)) 1.0) t_1))))
float code(float x, float tau) {
float t_1 = (x * ((float) M_PI)) * tau;
return sinf(t_1) * (fmaf((x * -0.16666666666666666f), (x * (((float) M_PI) * ((float) M_PI))), 1.0f) / t_1);
}
function code(x, tau) t_1 = Float32(Float32(x * Float32(pi)) * tau) return Float32(sin(t_1) * Float32(fma(Float32(x * Float32(-0.16666666666666666)), Float32(x * Float32(Float32(pi) * Float32(pi))), Float32(1.0)) / t_1)) end
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \left(x \cdot \pi\right) \cdot tau\\
\sin t\_1 \cdot \frac{\mathsf{fma}\left(x \cdot -0.16666666666666666, x \cdot \left(\pi \cdot \pi\right), 1\right)}{t\_1}
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Applied rewrites85.6%
Applied rewrites85.4%
Final simplification85.4%
(FPCore (x tau) :precision binary32 (* (/ (sin (* x PI)) (* x PI)) (fma (* x x) (* -0.16666666666666666 (* tau (* tau (* PI PI)))) 1.0)))
float code(float x, float tau) {
return (sinf((x * ((float) M_PI))) / (x * ((float) M_PI))) * fmaf((x * x), (-0.16666666666666666f * (tau * (tau * (((float) M_PI) * ((float) M_PI))))), 1.0f);
}
function code(x, tau) return Float32(Float32(sin(Float32(x * Float32(pi))) / Float32(x * Float32(pi))) * fma(Float32(x * x), Float32(Float32(-0.16666666666666666) * Float32(tau * Float32(tau * Float32(Float32(pi) * Float32(pi))))), Float32(1.0))) end
\begin{array}{l}
\\
\frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \cdot \mathsf{fma}\left(x \cdot x, -0.16666666666666666 \cdot \left(tau \cdot \left(tau \cdot \left(\pi \cdot \pi\right)\right)\right), 1\right)
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
+-commutativeN/A
*-commutativeN/A
associate-*r*N/A
associate-*l*N/A
*-commutativeN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
unpow2N/A
associate-*l*N/A
lower-*.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f3278.6
Applied rewrites78.6%
Final simplification78.6%
(FPCore (x tau) :precision binary32 (let* ((t_1 (* (* x x) -0.16666666666666666))) (* (fma (* PI PI) t_1 1.0) (fma (* tau (* tau (* PI PI))) t_1 1.0))))
float code(float x, float tau) {
float t_1 = (x * x) * -0.16666666666666666f;
return fmaf((((float) M_PI) * ((float) M_PI)), t_1, 1.0f) * fmaf((tau * (tau * (((float) M_PI) * ((float) M_PI)))), t_1, 1.0f);
}
function code(x, tau) t_1 = Float32(Float32(x * x) * Float32(-0.16666666666666666)) return Float32(fma(Float32(Float32(pi) * Float32(pi)), t_1, Float32(1.0)) * fma(Float32(tau * Float32(tau * Float32(Float32(pi) * Float32(pi)))), t_1, Float32(1.0))) end
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \left(x \cdot x\right) \cdot -0.16666666666666666\\
\mathsf{fma}\left(\pi \cdot \pi, t\_1, 1\right) \cdot \mathsf{fma}\left(tau \cdot \left(tau \cdot \left(\pi \cdot \pi\right)\right), t\_1, 1\right)
\end{array}
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Taylor expanded in x around 0
+-commutativeN/A
associate-*r*N/A
*-commutativeN/A
associate-*l*N/A
associate-*r*N/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
Applied rewrites78.4%
Final simplification78.4%
(FPCore (x tau) :precision binary32 (fma (* x (* x (* PI PI))) (fma -0.16666666666666666 (* tau tau) -0.16666666666666666) 1.0))
float code(float x, float tau) {
return fmaf((x * (x * (((float) M_PI) * ((float) M_PI)))), fmaf(-0.16666666666666666f, (tau * tau), -0.16666666666666666f), 1.0f);
}
function code(x, tau) return fma(Float32(x * Float32(x * Float32(Float32(pi) * Float32(pi)))), fma(Float32(-0.16666666666666666), Float32(tau * tau), Float32(-0.16666666666666666)), Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(x \cdot \left(x \cdot \left(\pi \cdot \pi\right)\right), \mathsf{fma}\left(-0.16666666666666666, tau \cdot tau, -0.16666666666666666\right), 1\right)
\end{array}
Initial program 98.1%
lift-*.f32N/A
lift-/.f32N/A
associate-*r/N/A
frac-2negN/A
lower-/.f32N/A
Applied rewrites97.9%
Taylor expanded in x around 0
+-commutativeN/A
+-commutativeN/A
distribute-rgt-inN/A
associate-*r*N/A
*-commutativeN/A
associate-*r*N/A
associate-*r*N/A
*-commutativeN/A
distribute-rgt-outN/A
Applied rewrites77.6%
(FPCore (x tau) :precision binary32 (fma (* x x) (* (* PI PI) (fma -0.16666666666666666 (* tau tau) -0.16666666666666666)) 1.0))
float code(float x, float tau) {
return fmaf((x * x), ((((float) M_PI) * ((float) M_PI)) * fmaf(-0.16666666666666666f, (tau * tau), -0.16666666666666666f)), 1.0f);
}
function code(x, tau) return fma(Float32(x * x), Float32(Float32(Float32(pi) * Float32(pi)) * fma(Float32(-0.16666666666666666), Float32(tau * tau), Float32(-0.16666666666666666))), Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(x \cdot x, \left(\pi \cdot \pi\right) \cdot \mathsf{fma}\left(-0.16666666666666666, tau \cdot tau, -0.16666666666666666\right), 1\right)
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
+-commutativeN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
associate-*r*N/A
distribute-rgt-outN/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
+-commutativeN/A
lower-fma.f32N/A
unpow2N/A
lower-*.f3277.6
Applied rewrites77.6%
(FPCore (x tau) :precision binary32 (* (fma (* PI PI) (* (* x x) -0.16666666666666666) 1.0) 1.0))
float code(float x, float tau) {
return fmaf((((float) M_PI) * ((float) M_PI)), ((x * x) * -0.16666666666666666f), 1.0f) * 1.0f;
}
function code(x, tau) return Float32(fma(Float32(Float32(pi) * Float32(pi)), Float32(Float32(x * x) * Float32(-0.16666666666666666)), Float32(1.0)) * Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(\pi \cdot \pi, \left(x \cdot x\right) \cdot -0.16666666666666666, 1\right) \cdot 1
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Taylor expanded in x around 0
Applied rewrites64.0%
Final simplification64.0%
(FPCore (x tau) :precision binary32 (* (fma (* PI PI) (* x (* x -0.16666666666666666)) 1.0) 1.0))
float code(float x, float tau) {
return fmaf((((float) M_PI) * ((float) M_PI)), (x * (x * -0.16666666666666666f)), 1.0f) * 1.0f;
}
function code(x, tau) return Float32(fma(Float32(Float32(pi) * Float32(pi)), Float32(x * Float32(x * Float32(-0.16666666666666666))), Float32(1.0)) * Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(\pi \cdot \pi, x \cdot \left(x \cdot -0.16666666666666666\right), 1\right) \cdot 1
\end{array}
Initial program 98.1%
Taylor expanded in x around 0
*-commutativeN/A
associate-*r*N/A
+-commutativeN/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f3285.6
Applied rewrites85.6%
Applied rewrites85.6%
Taylor expanded in x around 0
Applied rewrites64.0%
Final simplification64.0%
(FPCore (x tau) :precision binary32 1.0)
float code(float x, float tau) {
return 1.0f;
}
real(4) function code(x, tau)
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}
Initial program 98.1%
Taylor expanded in x around 0
Applied rewrites63.2%
herbie shell --seed 2024237
(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))))