Calculating values for a matrix to then be reused

I am looking for a way to place a calculated value into a matrix corresponding to the number used to calculate the matrix. Say I were to use variables 'a' through 'z' (a-z). The matrix I wish to compute will be a to z by a to z or 26 by 26. After calculating an answer involving variables f and g, such that function[f,g], this will be placed into the corresponding 'fg' element.

Also if the fg was to be used again in another calculation for say the 'gh' element, how can I reuse fg?

[Azzi Abdelmalek]

This is not clear

[mohammed]

can you give some small example? like your inputs and your desired output.

[Image Analyst]

What's wrong with

yourArray(f,g) = yourAnswer; % Assign yourAnswer to element (f,g).

???