Floating Point Modulo Operation

Question

I am trying to implement the range reduction operation for trigonometry. But instead I think it might be better to just perform a modulo pi/2 operation on incoming data. I

Answer 1

The algorithm you want, to limit a floating point value between 0 and some modulus n:

Double fmod(Double value, Double modulus)
{
    return value - Trunc(value/modulus)*modulus;
}

for example pi mod e (3.14159265358979 mod 2.718281828459045)

3.14159265358979 / 2.718281828459045 
   = 1.1557273497909217179

Trunc(1.1557273497909217179)
   = 1

1.1557273497909217179 - 1
   = 0.1557273497909217179

0.1557273497909217179 * e
   = 0.1557273497909217179 * 2.718281828459045
   = 0.42331082513074800

pi mod e = 0.42331082513074800