double __far fmod(double x, double y);
Returns a floating-point value that is the remainder resulting from dividing x by y.
If x or y is a Not-a-Number (NaN) , fmod returns a Not-a-Number (NaN) and sets macro EDOM to global variable errno.
If x is or y is zero, fmod returns a Not-a-Number (NaN) and sets macro EDOM to global variable errno.
If x is not or y is , fmod returns x and sets macro EDOM to global variable errno.
This function calculates a floating-point value that is the remainder resulting from dividing x by y. In other words, the value of "x - i * y" for integer i is calculated when y is not 0. The result has the same sign as that of x, and the absolute value is smaller than that of y.