Quantum Trace Distance from Trace Norm density-operator difference trace norm Solver

            from math import *

def quantum_trace_distance_solve_a(c, b) -> float:
    return ((c * 2.0) / b)

assert abs(quantum_trace_distance_solve_a(0.18, 1) - 0.36) < 1e-6 * max(1.0, abs(0.36))
          

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

double quantum_trace_distance_solve_a(double c, double b) {
    return ((c * 2.0) / b);
}

int main(void) {
    const double expected = 0.36;
    const double actual = quantum_trace_distance_solve_a(0.18, 1);
    assert(fabs(actual - expected) < 1e-6 * fmax(1.0, fabs(expected)));
}
          

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

double quantum_trace_distance_solve_a(double c, double b) {
    return ((c * 2.0) / b);
}

int main() {
    constexpr double expected = 0.36;
    const double actual = quantum_trace_distance_solve_a(0.18, 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 quantum_trace_distance_solve_a(double c, double b)
; Linux x86-64 NASM · System V ABI · first eight doubles in xmm0–xmm7
global quantum_trace_distance_solve_a
section .text

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

            function result = quantum_trace_distance_solve_a(c, b)
    result = ((c * 2.0) / b);
end
          

            ClearAll[mwCalculate];
mwCalculate[c_, b_] := ((c * 2.0) / b);