∑+

This operation takes a single real value or a single vector or matrix from the stack and adds the value(s) to the ∑DAT variable which holds the set of statistics values. The ∑DAT variable is always a real matrix which contains at least a single column of numbers. Each column represents a set of values for a single sample. The number of rows represents the number of samples in the statistics.

If the ∑DAT variable does not exist when this operation is executed, it will be created with the value(s) passed in. If a real value is passed in, the ∑DAT variable will be created and contain a 1x1 real matrix with the real value from the stack. If a real vector is on the stack, then the ∑DAT variable will contain real matrix with a single row. The number of columns in the real matrix will match the number of columns in the vector from the stack. Finally, if the argument on the stack is a real matrix, then that real matrix will be stored in the ∑DAT variable.

If the ∑DAT variable already exists, then the number of columns in the ∑DAT variable must match the number of values on the stack. If a real value is on the stack, then the ∑DAT has to be a real matrix with a single column. If it is, then the number of rows in the ∑DAT matrix is increased by one and the new value is added at the bottom of the ∑DAT matrix. If a real vector is on the stack, then the ∑DAT has to be a real matrix with the same number of columns as the vector from the stack. If so, then the ∑DAT variable has a new row added at the bottom with the values from the input vector. Finally, if a real matrix is on the stack, then the ∑DAT variable must have the same number of columns as the matrix from the stack. If so, then all rows from the input matrix are appended to the bottom of the ∑DAT matrix.