Category : C Source Code
Archive   : DYNAM_S1.ZIP
Filename : YDBLVDP.C

/********************** YDblVdp for double vanderPol *************************/
/********************* (C) 1986,7,8 by JAMES A. YORKE ************************/

#include "yinclud.h"

DEDblVdp(k, Y) /* 2 coupled vanderpol oscillators -- see also
map 23 */
double k[],
Y[];
{
int i;
double tval, /* t is a global variable */
s,
X1,
X2,
Y1,
Y2;
int base;
tval = Y[0];
X1 = Y[1];
Y1 = Y[2];
X2 = Y[3];
Y2 = Y[4];
s = rho * sin(C4 * tval);
k[0] = 1;
k[1] = Y1;
k[2] = C1 * Y1 * (1 - X1 * X1) - C2 * X1 - C3 * X1 * X1 * X1 + s + rho * X2;

k[3] = Y2;
k[4] = C5 * Y2 * (1 - X2 * X2) - C6 * X2 - C7 * X2 * X2 * X2 + s + rho * X1;

if(num_lyap > 0) {
for(i = 0; i < num_lyap; i++) {
base = lyapzero + vec_dim * i;
k[base] = Y[base + 1];
k[base + 1] = (-2 * C1 * X1 * Y1 - C2 - 3 * C3 * X1 * X1) * Y[base]
+ C1 * (1.- X1 * X1) * Y[base + 1]
+ rho * Y[base + 2];
k[base + 2] = Y[base + 3];
k[base + 3] =
rho * Y[base]
+ (-2 * C5 * X2 * Y2 - C6 - 3 * C7 * X2 * X2) * Y[base + 2]
+ C5 * (1 - X2 * X2) * Y[base + 3];
}
}
}
v2_mod() {
double moduloAB();
y[0] = moduloAB(y[0], 0., twopi / C4);/* time */
modFlag = NO;
/* bring y[1] and y[3] into -pi,pi etc. */
y[1] = moduloAB(y[1], -pi, pi);
y[3] = moduloAB(y[3], -pi, pi);
}


initDblVanderpol() {
extern int DEDblVdp(), v2_mod ();
zeroth = 1;
vec_dim = 4; /* the dimension of the Lyapunov vectors =
phase space dim */
num_lyap = 0; /* the number of Lyapunov numbers to be
computed <= vec_dim */
lyapzero = 5; /* y[lyapzero] is the zeroth coord of the
zeroth lyapunov vector */
dim = lyapzero + num_lyap * vec_dim;
/* needed for rungekutta */
X_upper = 2.2; /* x scale */
X_lower = -2.2;
Y_upper = 3.3; /* y scale */
Y_lower = -3.3;
X_coord = 1;
Y_coord = 2;
C1 = 2./ 5.;
C2 = 0.;
C3 = 1.;
C4 =.6;
C5 = 1./ 5.;
C6 = 0.;
C7 = 1.;
rho = 1.0;
steps_per_cycle = 40;
step = (twopi / C4) / steps_per_cycle;
DE = DEDblVdp; /* DE is a pointer to a function */
modPointer = v2_mod;
}