main.c

#include "rc.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <plplot.h>

#define NSIZE 5000

int main(int argc, char *argv[]) {
    rc_state rc = rc_state_create(1.0, 1.0, 1.0);


// ============================================================ //
// RC with constant != 0 tension at input and 0 initial tension //
// ============================================================ //
    double v, v_ini;
    v = v_ini = 0.0;

    double dt = 0.001;
    double max_t = 5.0;

    PLFLT x[NSIZE], y[NSIZE];
    PLFLT xmin = 0., xmax = max_t, ymin = rc.eps-1, ymax = rc.eps+1;

    for (double t = 0.0; t < max_t; t += dt) {
        double ve = exact_solution(t, v_ini, &rc);
        printf("t = %f, v = %f, v_e = %f, diff = %f\n", t, v, ve, ve - v);
        v = rc_advance(v, dt, &rc);
    }

    v = v_ini = 1.0;
    double omega = 10.0;
    int i = 0;
    for (double t = 0.0; t < max_t; t += dt) {
        rc.eps = v_ini * (1.0 + cos(omega * t));
        double ve = exact_solution(t, v_ini, &rc);
        printf("t = %f, v = %f, v_e = %f, diff = %f\n", t, v, ve, ve - v);
        x[i] = t;
        y[i] = v;
        v = rc_advance(v, dt, &rc);
        i += 1;
    }

    // Parse and process command line arguments
    plparseopts( &argc, argv, PL_PARSE_FULL );

    // Initialize plplot
    plinit();

    // Create a labelled box to hold the plot.
    plenv( xmin, xmax, ymin, ymax, 0, 0 );
    pllab( "t", "v", "Simple PLplot demo of of the charge of a capacitor" );

    // Plot the data that was prepared above.
    plline( NSIZE, x, y );

    // Close PLplot library
    plend();

    return EXIT_SUCCESS;
}