Webproject-Warmup

First project

C++ Eular

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

#define Tmax 50 // seconds for integration

main(argc,argv) int argc; char *argv[]; { double k,m,xt0,t0,vt0,vt,xt,t,dt,xtold,vtold; FILE *fout, *fopen();

fout = fopen("osc1.dat","w");

k = 1.0;                   // spring constant
m = 1.0;                   // mass in kg
xt0 = 1.0;                 // initial position
t0 = 0.0;                  // initial time
vt0 = 0.0;                 // initial velocity
dt = 0.001;		   // time interval

xtold = xt0;               // set & print out the initial conditions
vtold = vt0;
t = t0;
fprintf(fout,"%e\t%e\t%e\n",t, xt0,vt0);

/* Here is the loop that propagates the motion: vt is for the new time, vtold the previous step time; xt is the new position, xtold the previous; after each step is calculated, the old is set to the new, and the cycle is repeated */

for(t=t0; t<Tmax; t+= dt){
	vt = vtold + dt*(-k/m)*xtold;
	xt = xtold + dt*vtold;
	xtold = xt;
	vtold = vt;
	fprintf(fout,"%e\t%e\t%e\n", t,xt,vt);
   }

}