SINC - Return SINC(x) for as floats or as doubles
fsinc return float value of sinc(x) for x input as a float
dsinc return double precision sinc(x) for double precision x
Function Prototype:
float fsinc (float x);
double dsinc (double x);
Input:
x value at which to evaluate sinc(x)
Returned: sinc(x)
Notes:
sinc(x) = sin(PI*x)/(PI*x)
Author: Dave Hale, Colorado School of Mines, 06/02/89