#include <math.h>
#include <stdio.h>


const int sample_count = 32;
double sample[sample_count];

int main(int argc, char* argv[])
{
    double R = .089;	    // Resistance in Ohms
    double L = 0.000040;    // Inductance in Henrys
	double V = 12;          // Voltage
    double F = 120;         // Frequency in Hz
    double period = 1.0/F;  // Period in seconds
    double d = .1;           // duty cycle 0-1
    double Istart; // current at start of on and off cycle
	double I;               // Current
    int i,j;
    double time;

    I = 0;
    for(j=0;j<10;j++)       // loop several times so starting current can stabalize
    {
        // generate samples for on portion of ducy cylcle
        Istart = I; // current at start of on cycle
        for(i=0;i<(sample_count*d);i++)
        {
            time = i * (period / sample_count);

	        I = Istart+((V/R-Istart)*(1-exp(-time/(L/R))));

            sample[i] = I;
        }

        // generage samples for off portion of duty cycle
        Istart = I;  // current at start of off cycle
        for(i=i;i<sample_count;i++)
        {
            time = (i - sample_count*d) * (period / sample_count);

            I = Istart*exp(-time/(L/R));

            sample[i] = I;
        }
    }

    // Print samples and calulate RMS current
    double Isum = .0;
    for(i=0;i<sample_count;i++)
    {
        I = sample[i];
        printf("I = %f\n", I);
        Isum += I*I;
    }

    double Irms = sqrt(Isum/sample_count);
    printf("duty cycle = %f, Irms = %f\n",d,Irms);

	return 0;
}