v/vlib/math/modf.v at master · initdc/v

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module math

const modf_maxpowtwo = 4.503599627370496000e+15

// modf returns integer and fractional floating-point numbers

// that sum to f. Both values have the same sign as f.

// special cases are:

// modf(±inf) = ±inf, nan

// modf(nan) = nan, nan

pub fn modf(f f64) (f64, f64) {

abs_f := abs(f)

mut i := 0.0

if abs_f >= modf_maxpowtwo {

i = f // it must be an integer

} else {

i = abs_f + modf_maxpowtwo // shift fraction off right

i -= modf_maxpowtwo // shift back without fraction

for i > abs_f { // above arithmetic might round

i -= 1.0 // test again just to be sure

}

if f < 0.0 {

i = -i

}

return i, f - i // signed fractional part

}