FFT Angular Bin Spacing transform length Solver

            from math import *

def fft_angular_bin_spacing_solve_b(c, a) -> float:
    return (((2.0 * pi) * a) / c)

assert abs(fft_angular_bin_spacing_solve_b(0.09817477042468103, 1) - 64) < 1e-6 * max(1.0, abs(64))
          

            #include <assert.h>
#include <math.h>

double fft_angular_bin_spacing_solve_b(double c, double a) {
    return (((2.0 * 3.141592653589793) * a) / c);
}

int main(void) {
    const double expected = 64;
    const double actual = fft_angular_bin_spacing_solve_b(0.09817477042468103, 1);
    assert(fabs(actual - expected) < 1e-6 * fmax(1.0, fabs(expected)));
}
          

            #include <cassert>
#include <cmath>
#include <numbers>

double fft_angular_bin_spacing_solve_b(double c, double a) {
    return (((2.0 * std::numbers::pi) * a) / c);
}

int main() {
    constexpr double expected = 64;
    const double actual = fft_angular_bin_spacing_solve_b(0.09817477042468103, 1);
    assert(std::fabs(actual - expected) < 1e-6 * std::fmax(1.0, std::fabs(expected)));
}
          

x86-64 NASM · System V ABI · Linux · SSE2 with libm where required

            ; double fft_angular_bin_spacing_solve_b(double c, double a)
; Linux x86-64 NASM · System V ABI · first eight doubles in xmm0–xmm7
global fft_angular_bin_spacing_solve_b
section .text

fft_angular_bin_spacing_solve_b:
    push rbp
    mov rbp, rsp
    sub rsp, 64
    movsd [rbp-8], xmm0
    movsd [rbp-16], xmm1
    mov rax, 0x4000000000000000
    movq xmm0, rax
    movsd [rbp-48], xmm0
    mov rax, 0x400921fb54442d18
    movq xmm0, rax
    movsd [rbp-56], xmm0
    movsd xmm0, [rbp-48]
    mulsd xmm0, [rbp-56]
    movsd [rbp-40], xmm0
    movsd xmm0, [rbp-40]
    mulsd xmm0, [rbp-16]
    movsd [rbp-32], xmm0
    movsd xmm0, [rbp-32]
    divsd xmm0, [rbp-8]
    movsd [rbp-24], xmm0
    movsd xmm0, [rbp-24]
    leave
    ret
          

            function result = fft_angular_bin_spacing_solve_b(c, a)
    result = (((2.0 * pi) * a) / c);
end
          

            ClearAll[mwCalculate];
mwCalculate[c_, a_] := (((2.0 * Pi) * a) / c);