Trouble by function handling: "Inner matrix dimensions must agree."

Hi,

I would like to define one function with 2 variables, then to integrate it. As it is a long expression, I divided it into other functions.

C=etar*etap*Pp/(h*c/lambdap)*2*alpha/(pi*wp^2);
Rp=@(r,z)C*exp(-2*r*r/(wp*wp))*exp(-alpha*z);

zR=pi*w0^2/lambda;
w=@(z)w0*sqrt(1+(z/zR)^2);

Ne=@(r,z)Rp(r,z)*Tau;
Ng=@(r,z)Nt-Rp(r,z)*Tau;

BetaS=@(r,z)(Ne(r,z)-Ng(r,z))/(Ne(r,z)+Ng(r,z));

integrd1=@(r,z)BetaS(r,z)*exp(-2*r*r/(w(z)*w(z)))*r;
integrd2=@(r,z)exp(-2*r*r/(w(z)*w(z)))*r;

BetaSAv=dblquad(integrd1,0,Inf,0,lc)/dblquad(integrd2,0,Inf,0,lc);

All the constants are defined before. I have then the error message:

??? Error using ==> mtimes
Inner matrix dimensions must agree.

Error in ==> BetaSAvCalc2>@(r,z)C*exp(-2*r*r/(wp*wp))*exp(-alpha*z) at 28
    Rp=@(r,z)C*exp(-2*r*r/(wp*wp))*exp(-alpha*z);

The error message continue with all lines which have a failure. Could you please help me to understand what is wrong ? Thanks in advance !

Answer 1

[Walter Roberson]

You get that message when you try to use "*" to multiply two matrices and the second dimension of the first matrix does not match the first dimension of the second matrix. That is, "*" means "matrix multiplication".

Probably somewhere in your expression is a vector. You might be thinking you are squaring each element of the vector by multiply the vector by itself, but since "*" is matrix multiplication instead you get an error.

Convert your "*" in to ".*" and convert your "/" in to "./" except for the cases where you are sure that you want matrix multiplication (in the mathematical sense.)

Answer 2

[Anne-Laure]

Thanks, everywhere with ".*" and "./* it is working. I still can´t find any vector or matrix (I already checked that before posting).

[Walter Roberson]

dblquad() passes a vector as the first argument and a scalar as the second.