/* B-1; version 1.0 */
/* (c) copyright Ian Hickson 2000, distributed under the GNU GPL */

#include "dynamic-2d-arrays.h"
#include "lists.h"
#include "runge-kutta.h"

/* Circuit Constants */
#define C 4.7e-6
#define R 1e3
#define L1 20e-3
#define L2 10e-3

/* Details of range */
#define Start 0
#define End 20e-3
#define StepSize 1e-5

/* Differential Equation: 

   d2V   1  dV     1     1        1
   --- + -- -- + (--- + ---) V = --- e(t)
   dt2   RC dt    L1C   L2C      L2C
         \b/     \____c____/     \__d__/

 */

nlNumber e(nlNumber x) {
  return x < 5e-3 ? 1.0 : 0.0; 
}

nlNumber b(nlNumber x) {
  return 1/(R*C);
}

nlNumber c(nlNumber x) {
  return 1/(L1*C) + 1/(L2*C);
}

nlNumber d(nlNumber x) {
  return 1/(L2*C) * e(x);
}

nlNumber f1(nlNumber x, numberList* LastValues) {
   return d(x)-b(x)*nlGet(LastValues, 1)-c(x)*nlGet(LastValues, 0);
}

nlNumber printResult(nlNumber x, numberList* LastValues) {
  printf("%f,%f\n", x, nlGet(LastValues, 0));
}

main() {
  numberList* InitialValues;
  InitialValues = nlAllocList(2);
  nlSet(InitialValues, 0, 0);
  nlSet(InitialValues, 1, 0);
  rungekutta(Start, End, StepSize, InitialValues, &f1, &printResult);
  nlFreeList(InitialValues);
}