in this program for the temperature, i have the error "this value must a vector", Please help me 
In my opinion your program is far too large and clutterd and should be split into parts.
The error is thrown at this line
because A is not a vector but a 3 x 3 matrix (and would require tw indices zo access elements).
The argument vector A is overwritten by your program here
and is a 3 x 3 matrix because you made the variable a a 3 x 3 matrix here:
Regards Werner
There are many products poorly written. That is, to make the product, you have not used the product operator. The program is full of such errors.
The dot corresponding to the product is sometimes seen and sometimes not. It seems to me a mistake.
Bye
zbs:
By changing the Matrix a to a vector, the program runs until the while loop. However the exponential, in the first for loop of the while loop, overflows
