symbols in mathcad

You mean the curved and the straight arrow next to the summation symbol?

They do not exist in Mathcad. You might be able to find the symbols for those arrows in a font, but they will not have any special meaning (and certainly not the meaning you understand them to have!) in Mathcad, but you might be able to define functions for the symbols with the proper meaning.

What Mathcad has is a summation symbol (Greek uppercase letter sigma) with:

- no additional description: apply to a vector and it will give you the sum of all vector elements.

- a placeholder for a range variable (index). The range variable must be defined beforehand.

- a placeholder for a variable name (index) and start value below it, and a placeholder for an upper limit above it. 

Apply the last two forms to a vector or matrix and they will give you the sum of all elements that are indicated by the index from start to end.

Here's an example:

Success!
Luc

Attached is an example of a definition with an up-arrow Sigma.