VOLUME

MATRIX

 Syntax: VOLUME\MATRIX { x y } m { volm }
 Defaults: x=[1;2;...], y=[1;2;...]

 If the \MATRIX qualifier is used, a matrix is expected. The grid region is
 triangulated. The volume is approximated by summing the averages of the
 matrix values at the triangle vertices multiplied by the area of each
 triangle. If x and y are not entered then x defaults to [1;2;...;ncol] and
 y defaults to [1;2;...;nrow], where ncol is the number of columns of the
 matrix and nrow is the number of rows. The \POLAR qualifier is not allowed
 with matrix data.