added plplot to test. not sure if it's cool enough though

practical_work/rc_circuit/Makefile

 CC=clang
 OPTS=-g -O3 -Wall -Wextra -fsanitize=address -fsanitize=leak -std=c11
-LINK=-lm -fsanitize=address -fsanitize=leak
+INCLUDE=-I/usr/include/plplot/
+LINK=-lm -fsanitize=address -fsanitize=leak  -lplplot
 
 # OPTS=-g -O3 -Wall -Wextra -std=c11
 # LINK=-lm
@@ -9,7 +10,7 @@ main: main.o rc.o ode_o1.o
 	$(CC) $(OPTS) -o $@ $^ $(LINK)
 
 main.o: main.c
-	$(CC) $(OPTS) -c $^
+	$(CC) $(OPTS) $(INCLUDE) -c $^
 
 ode_o1.o: ode_o1.c ode_o1.h
 	$(CC) $(OPTS) -c $^

practical_work/rc_circuit/main.c

 #include "rc.h"
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
+#include <plplot.h>
 
-int main() {
+#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;
+    int i = 0;
+
+    PLFLT x[NSIZE], y[NSIZE];
+    PLFLT xmin = 0., xmax = max_t, ymin = 0., ymax = rc.eps;
+
     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);
+        x[i] = t;
+        y[i] = v;
         v = rc_advance(v, dt, &rc);
+        i += 1;
     }
 
+    v = v_ini = 1.0;
+    double omega = 0.0;
+    for (double t = 0.0; t < max_t; t += dt) {
+        rc.eps = sin(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);
+        v = rc_advance(v, dt, &rc);
+    }
+
+    // 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;
 }
\ No newline at end of file