STO∑

This operation takes the item from the top of the stack and stores it into a variable called ∑DAT. If the ∑DAT variable already contains a value, that value is overwritten by the value from the stack.

Although any value can be stored into the ∑DAT variable, it is expected that a real matrix will be stored into that variable. The stats operations expect a real matrix where every row represents a sample and each column contains one of the values from that sample. If you store anything other than a real matrix in the ∑DAT variable, most other stats operations will fail.