2.1. sinc examples

See chapter4_1.c & chapter4_2.c - try it -> plot, sinc.c

  #define PI (4*atan(1))

  double sinc( double x)
  {
    if( fabs(x) < 0.0001)
      return 1.0;
    else
      return sin(PI*x)/(PI*x);
  }

Example with local variables:

  double sinc( double x)
  {
    double r, t;

    if( fabs(x) < 0.0001)
      r = 1.0;
    else
    {
      t = PI*x;
      r = sin(t)/(t);
    }

    return r;
  }