sum_counterdiag {qfratio}

Summing up counter-diagonal elements

Description

sum_counterdiag() sums up counter-diagonal elements of a square matrix from the upper-left; i.e., c(X[1, 1], X[1, 2] + X[2, 1], X[1, 3] + X[2, 2] + X[3, 1], ...) (or a sequence of \sum_{i=1}^k x_{i, k - i + 1} for k = 1, 2, ...). sum_counterdiag3D() does a comparable in a 3D cubic array. No check is done on the structure of X.

Usage

sum_counterdiag(X)

sum_counterdiag3D(X)

Arguments

X

Square matrix or cubic array