Why the myfunction return zero elements?
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Muna Shehan
le 17 Juil 2016
Commenté : Muna Shehan
le 18 Juil 2016
Hi all; I have a function which should return a R_gradient matrix. I identify its elements but when I call myfunction it returns zero elements. I checked the passing parameter kc there is nothing wrong with it and the values of the elements are calculated correctly when i calculated them separately (i.e. Rg22,....,Rg55). can any one explain what wrong with myfunction. Regards
function R_gradient = myfunction(kc)
r1 = 1e+5;
r2 = 0.5;
q = 1e-5;
ks = kc(1);
cs = kc(2);
param.ms = 325;
param.mus = 65;
param.kus = 232.5e3;
param.ct = 0 ;
Rg22=r2*(cs/param.ms)^2;
Rg23=-r2*(cs/param.ms)*(ks/param.ms);
Rg24=-r2*(cs/param.ms)^2;
Rg25=r2*cs/(param.ms^2);
Rg32=-r2*(cs/param.ms)*(ks/param.ms);
Rg33=r2*(ks/param.ms)^2;
Rg34=r2*(cs/param.ms)*(ks/param.ms);
Rg35=-r2*ks/(param.ms^2);
Rg42=-r2*(cs/param.ms)^2;
Rg43=r2*(cs/param.ms)*(ks/param.ms);
Rg44=r2*(cs/param.ms)^2;
Rg45=-r2*cs/(param.ms^2);
Rg52=r2*cs/(param.ms^2);
Rg53=-r2*ks/(param.ms^2);
Rg54=-r2*cs/(param.ms^2);
Rg55=q+r2/(param.ms^2);
R_gradient = [
r1 0 0 0 0;...
0 Rg22 Rg23 Rg24 Rg25;...
0 Rg32 Rg33 Rg34 Rg35;...
0 Rg42 Rg43 Rg44 Rg45;...
0 Rg52 Rg53 Rg54 Rg55];
end
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Star Strider
le 17 Juil 2016
I don’t know what your ‘kc’ is, but when I do this:
kc = [1 2];
R_gradient = myfunction(kc)
I get this:
R_gradient =
1e+05 0 0 0 0
0 1.8935e-05 -9.4675e-06 -1.8935e-05 9.4675e-06
0 -9.4675e-06 4.7337e-06 9.4675e-06 -4.7337e-06
0 -1.8935e-05 9.4675e-06 1.8935e-05 -9.4675e-06
0 9.4675e-06 -4.7337e-06 -9.4675e-06 1.4734e-05
I don’t understand the problem. What do you want it to do?
2 commentaires
Star Strider
le 18 Juil 2016
My pleasure.
I do not understand what you want your ‘myfunction’ to do. If you are doing nonlinear optimisation and want to check its convergence, I would use the norm function with a tolerance. It will approach zero but will likely not ever uniformly equal zero.
If you are doing nonlinear optimisation, you need to use the output of ‘myfunction’ to change the values of ‘kc’ in your code from iteration to iteration until the gradient approximates zero within an acceptable tolerance. (The usual default tolerance is 1.0E-8 in most such applications.)
I am guessing what you are doing. This is the best I can do.
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Walter Roberson
le 17 Juil 2016
If you getting out a matrix in which all except one entry are 0, then you need to give the command
format long g
and then look at the outputs again.
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