#include "ezInc3.h"

/* global variables -- but private to this file */
static double ppw = 0, cdtds;

/* prompt user for source-function points per wavelength */
void ezIncInit(Grid *g){

  cdtds = Cdtds;  
  printf("Enter points per wavelength: ");
  scanf(" %lf", &ppw);

  return;
}

/* calculate source function at given time and location */
double ezInc(double time, double location) {
  if (ppw <= 0) {
    fprintf(stderr,
       "ezInc: must call ezIncInit before ezInc.\n"
       "       Points per wavelength must be positive.\n");
    exit(-1);
  }

  return sin(2.0 * M_PI / ppw * (cdtds * time - location));
}