modf - extract signed integral and fractional values from floating-point number
Library Synopsis Description Return Values See Also Standards
.In math.h double modf "double value" "double *iptr"
The modf function breaks the argument value into integral and fractional parts, each of which has the same sign as the argument. It stores the integral part as a .Vt double in the object pointed to by iptr.
The modf function returns the signed fractional part of value.
frexp(3), ldexp(3), math(3)