Euler

You will find this code in the EJS console at page Initialization.

lines marked //  include remarks that do not influence the calculation.

xE[0]=0;

yE[0]=Anfangswert;

AbleitungE[0]=yE[0];//for exponential

for (int i=1; i<n; i++) {//loop definitionn)

xE[i]=xE[i-1]+delta;

yE[i]=yE[i-1]+delta*AbleitungE[i-1];

AbleitungE[i]=yE[i];//for exponential

//bach to start of loop

FE[i]=(Anfangswert*Math.exp(xE[i])-yE[i])/(Anfangswert*Math.exp(xE[i]));

}

Heun

xH[0]=0;

yH[0]=Anfangswert;

AbleitungH_a[0]=yH[0];//for exponential

for (int i=1; i<n; i++) {//loop definition)

xH[i]=xH[i-1]+delta;

yH_a[i]=yH[i-1]+delta*AbleitungH_a[i-1];

AbleitungH_b[i]=yH_a[i];////for exponential

yH[i]=yH[i-1]+delta/2*(AbleitungH_a[i-1]+AbleitungH_b[i]);

AbleitungH_a[i]=yH[i];////for exponential

//back to loop

FH[i]=(Anfangswert*Math.exp(xH[i])-yH[i])/(Anfangswert*Math.exp(xH[i]));

}