Asked by TALA MOUSSA
on 29 Nov 2011

hi , Im a beginner in using matlab , i tried several times to debug my program but the error is still the same!! can you help me please:) Thanks

clear clear all

global kfiler d kmatrice phi kmes kcalc y s Rcmin kcalcmin Rc kmatrice=[29.16;0;0;0;0]; kfiler=2000; d=91e-6;

kmes = [29.16;31.51;36.33;39.9;44.3];

phi = [0 0 0 0 0;0 7.4 0 0 0;0 0 11.52 0 0; 0 0 0 18.44 0;0 0 0 0 23.88];

kcalc=kmatrice*(2*kmatrice+(kfiler/(1+2*(kfiler*Rc/d)))-2*phi*(kmatrice-(kfiler/(1+2*(kfiler*Rc/d)))))/(2*kmatrice+(kfiler/(1+2*(kfiler*Rc/d)))+phi*(kmatrice-(kfiler/(1+2*(kfiler*Rc/d))))); y= (kmes-kcalc)^2;

s= @(Rc)sum(y); kcalcmin = fminsearch(s,kmatrice);

Rcmin=(kfiler/kcalcmin-1)*d/(2*kfiler);

Rcmin

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Answer by Sven
on 29 Nov 2011

Accepted answer

**Rc** is empty (it gets initialised as a global variable but nothing is assigned to it), but it's used in your **calc=...** calculation.

Was this intentional?

The problem here is that anything multiplied by an empty [] will return []. And any non-empty matrix *divided* by an empty matrix will cause an error.

The final part of your calculation:

kfiler/(1+2*(kfiler*Rc/d))

Is one such part. **kfiler** is not empty, but **Rc** (and consequently **(1+2**(kfiler*Rc/d))* is empty.

You'll get the same error if you type in:

100 / []

One small suggesion: break up your calculation into a few lines. Otherwise it will be a complete nightmare to debug because all error messages will point to this one huge line (which doesn't help you track them down)

TALA MOUSSA
on 29 Nov 2011

Answer by Walter Roberson
on 29 Nov 2011

TALA MOUSSA
on 30 Nov 2011

Is anyone knows how to use the least square regression method in matlab?

Opportunities for recent engineering grads.

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