How to do modulus with floats and doubles in C

You may be tempted to use the '%' operator but that's only for integers.
To do modulus arithmetic with doubles and floats use the math.h library.
Use the following functions:

       double fmod(double x, double y);
       float fmodf(float x, float y);
       long double fmodl(long double x, long double y);

Use -lm to link to the library.