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Topic: symbolic in FOR loop. not run...WHy??
Replies: 1   Last Post: Dec 31, 2012 12:48 AM

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 Steven Lord Posts: 18,038 Registered: 12/7/04
Re: symbolic in FOR loop. not run...WHy??
Posted: Dec 31, 2012 12:48 AM

"Quynh Tram Nghuyen Thi" <lovelyeverything@yahoo.com.vn> wrote in message
news:kb29gd\$ltb\$1@newscl01ah.mathworks.com...
> Helloo all,
> I may put a question about symbolic & for loop. I AM USING FOR loop to
> construct functions as following:
>
> (M-FILE)
> syms x y
> for i=1:4
> N(i,1)=(x-1)*(y-1);N(i+4,1)=(x-5+i)*(y-2);

*snip*

If N is a double array already, this will need to convert (x-1)*(y-1) into a
double precision value in order to store that value in an element of N.
However, since you haven't specified a value for x or y, it cannot perform
that conversion and so throws the error. Either specify NUMERIC values for x
and y in your script/function [so that (x-1)*(y-1) results in a numeric
value which can be converted to a double precision value] or initialize N
symbolically before running this loop so MATLAB doesn't need to convert the
symbolic (x-1)*(y-1) to perform the assignment.

N = sym(zeros(4, 4));

--
Steve Lord
slord@mathworks.com