/*
 * functions.c - these little functions are intended as arguments to plot().
 *               See plot.c.
 */

#include <math.h>
#include "functions.h"

double identity(double y)
{
    return y;
}

double odd(double y)  /* basically, says whether or not floor(y) is odd */
{
    int i = floor(y);
    if (i % 2 == 0)
        return -999;
    else
        return y;
}

double square(double y)
{
    return y * y;
}

double sine(double y)
{
    return 3 * sin(y);
}

double cubic(double y)  /* y**3 - 2y + 1 */
{
    return (y * y * y - 2 * y + 1) ;
}