Error using ==> mrdivide Out of memory

Hi, this is my code;

r=10
for i=1:r

    Cs=1.17 
    Cc=2.37 
    v=0.0000711 
    kg=0.0457 
    kp=0.26 
    Ct=2.18
    Kn=0.1 
    Cm=1.14
    T=temperature(i,:); 

    Vtx=(((2*Cs*Cc*v)*((kg/kp)+(Ct*Kn)))/((1+(3*Cm*Kn))...
        *(1+2*(kg/kp)+(2*Ct*Kn))))*(1/T)*(Delta_temperature/Delta_x); 

end

Then, there is an error comes out;

??? Error using ==> mrdivide Out of memory. Type HELP MEMORY for your options.

Error in ==> Vtx=(((2*Cs*Cc*v)*((kg/kp)+(Ct*Kn)))/((1+(3*Cm*Kn))...

What is actually happen?

p/s: Delta_temperature & Delta_x already defined...

Answer 1

[Walter Roberson]

You have

    T=temperature(i,:); 

    Vtx=(((2*Cs*Cc*v)*((kg/kp)+(Ct*Kn)))/((1+(3*Cm*Kn))...
        *(1+2*(kg/kp)+(2*Ct*Kn))))*(1/T)*(Delta_temperature/Delta_x);

T is a column vector, so 1/T is a request to do a Matrix Right Division. That takes more memory than a plain division -- it would require at least one matrix length(T) by length(T) to build the vandermode matrix, and then some other working memory (quite possibly another matrix the same size as that.)

Perhaps you want 1./T instead of 1/T ?

[Fadzli]

Thank you sir, I think I got the point...

Answer 2

[Jan]

The dimensions of the already defined variables Delta_temperature and Delta_x matter. If they are [N, 1] and [M, 1] vectors, the result is a [N, M] matrix. It seems like the creation of this matrix exhaust your memory.

There are several methods to cope with this problem:

1. Install more RAM
2. Consider if this is a bug and you want an elementwise division with the ./ operator.
3. Install more RAM
4. Close other applications
5. Use single precision, if applicabale and accurate enough for the problem
6. Install more RAM and care for using a 64 bit Matlab, such that the RAM can be used
7. Clear unused variables. Most of all compute large arrays outside the loop and once only
8. Check the sizes of the concerned variables - perhaps there is a bug before
9. And, you can guess it, install more RAM ;-)

[Fadzli]

Thank you sir, I think I got the point...