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Topic: Matrix formed in for loop
Replies: 1   Last Post: Feb 27, 2013 11:50 AM

 Steven Lord Posts: 18,038 Registered: 12/7/04
Re: Matrix formed in for loop
Posted: Feb 27, 2013 11:50 AM

"Lakshmi " <guesswho1705@yahoo.com> wrote in message
news:kgjj2k\$6p0\$1@newscl01ah.mathworks.com...
> Hi
>
> I am trying to generate a matrix in a for loop with it's elements as
> symbols rather than actual numbers. I want to later use this matrix in
> another loop where the symbols values are assigned but the values change
> with every loop.
> Initially I had tried putting the loop developing the matrix within the
> loop that gives the values, but it threw an error saying number of matrix
> elements should be definite.
>
> The problem I am having currently is when I execute this piece of code
> for cc1=1:4
> for cc2=1:4
> for cc3=1:4
> for cc4=1:4
> Tc(ac,1)=expand(T1(cc1))*(T2(cc2))*(T3(cc3))*(T4(cc4));
> ac=ac+1;
> end
> end
> end
> end
>
> where T1,2,3,4 are matrices with symbolic elements,
>
> I get this error
> ??? The following error occurred converting from sym to double:
> Error in MuPAD command: DOUBLE cannot convert the input expression into a
> double array.
>
> If the input expression contains a symbolic variable, use the VPA function

Preallocate Tc to be a _symbolic_ matrix not a numeric matrix.

Tc = sym(zeros(4^4, 1));

--
Steve Lord
slord@mathworks.com
http://www.mathworks.com