What is the difference between sum and symsum

could anyone tell me what is the difference between sum and symsum

Answer 1

[KSSV]

sum works on double......it add the given numbers across specified dimension.

symsum works on symbolic variables.

You may read the documentation further.

Answer 2

[Walter Roberson]

symsum should only be used for calculating the formula for indefinite summations (or, sometimes, very large definite summations.) For example

syms k x
symsum(x^k/factorial(k), k, 1, inf)

symsum knows this is exp(x)

If you are adding up a finite list of distinct terms, you should probably be calculating the terms using vector calculations (and possibly subs() a vector of values into a symbolic expression) and then use sum() -- even if you are adding up symbolic expressions.

symsum() can never be used to index an array with a symbolic variable. You cannot use

symsum(x(k)/2^k, k, 1, length(x))     %wrong!!

for example.