in a function my answer is 'S=-102'. after that further more i cannot take answers , it give error massage saying

answer ==== S=-102 ''Attempted to access (-102); index must be a positive integer or logical.'' why is this and what is the solution for this.

[Geoff Hayes]

shashika - given the error message, it sounds like you are trying to use S (which is negative) as an index into array. Perhaps something like

 someArray(S)

As the error message states, the index must be a positive integer or logical. Your S is negative so using this value to access an element in an array does not make sense. You need either to guard against using a negative index or ensure that the code which initializes S only does so with valid positive integers.