Normalisation inside ODE function

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IISc 2014-8-19

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Dear All,

I have a issue descibed as follows

The following are the Euler integration equations in the original code inside a while loop

    Var1 = Var1 + dVar1 * delt;
    Var2 = Var2 + dVar2 * delt;
    Vau3 = Var3 + dVar3 * delt;
    Var4 = Var4 + dVar4 * delt;

tnor = sqrt(Var1*Var1 + Var2*Var2 + Vau3*Var3 + Var4*Var4);

         Var1 = Var1 / tnor;
         Var2 = Var2 / tnor;
         Vau3 = Var3 / tnor;
         Var4 = Var4 / tnor;

Iam reqriting using ODE method based code (in built matlab function). There seems to be issue the way normalisation of Var1, Var2, Var3, Var4 is to be done. If i do not do the normalisation the two codes match. (of the course the results will not be correct. The variables need to be normalised before next step of integration).

How should i implement the above last five lines so that when the solver evaluates the function in the next iteration it uses the normalised value for Var1, Var2, Var3 & Var4. Currently in ODEFUN i was doing this in beginning by writing

tnor = Y(1 )+ Y(2) + Y(3) + Y(4)

Y(1) = Y(1)/tnor

Y(2) = Y(2)/tnor

Y(3) = Y(3)/tnor

Y(4) = Y(4)/tnor

This does not work.

Regards,

Tarun Uppal