[mg87015] Re: Collect coefficients of array variables during calculation:

[Szabolcs Horvát <szhorvat at gmail.com>]

Gopinath Venkatesan wrote:
> Hello Mathematica Friends
> 
> If we have an array variable, and assuming after intermediate calculations, some equations are found to be below.
> 
> eqn1=10. A[[1,1]]+b A[[1,1]]+c A[[1,2]]+3. A[[1,2]] (only for illustration)
> 
> Simplify[] does not combine the coefficients under same array member, i.e. instead of (10.+b)A[[1,1]]+(c+3.)A[[1,2]], it is showing the earlier mentioned form.
> 
> Is there a way to collect them and simplify them. But when I checked for simple cases, Simplify[] seems to work.
> 
> Thanks for the suggestions.

A[[1,1]] evaluates to something if A is a compound expression.  If A is 
not a compound expression, then it is not correct to write A[[1,1]], and 
Mathematica will print an error message.

So A[[1,1]] can never appear in the result of a successful calculation.