698(2): デフォルトの名無しさん [] 2023/12/09(土) 19:54:16.97 ID:DXmw58tM(3/4) AAS
浮動小数点数使って弧度法で角度を表すことに何の疑問も持たない人は

#include <iostream>
#include <numbers>
#include <cmath>

int main()
{
　　for (int i = 0; i <= 8; i++) {
　　　　double s = sin(i / 4.0 * std::numbers::pi);
　　　　double c = cos(i / 4.0 * std::numbers::pi);
　　　　printf("sin(%d/4π) = %19.16f cos(%d/4π) = %19.16f\n", i, s, i, c);
　　}
}

sin(0/4π) = 0.0000000000000000 cos(0/4π) = 1.0000000000000000
sin(1/4π) = 0.7071067811865475 cos(1/4π) = 0.7071067811865476
sin(2/4π) = 1.0000000000000000 cos(2/4π) = 0.0000000000000001
sin(3/4π) = 0.7071067811865476 cos(3/4π) = -0.7071067811865475
sin(4/4π) = 0.0000000000000001 cos(4/4π) = -1.0000000000000000
sin(5/4π) = -0.7071067811865475 cos(5/4π) = -0.7071067811865477
sin(6/4π) = -1.0000000000000000 cos(6/4π) = -0.0000000000000002
sin(7/4π) = -0.7071067811865477 cos(7/4π) = 0.7071067811865474
sin(8/4π) = -0.0000000000000002 cos(8/4π) = 1.0000000000000000

外部ﾘﾝｸ:wandbox.org

sin(1/4π)とsin(3/4π)の結果が一致しないことやsin(8/4π)が0.0ちょうどに
ならないことは気にしないんだろうか?