sum (expr, dim1, dim2, <,tinc> <,-b>)

Sums the result of expr over the specified dimension range. If the summing dimension is time, an optional time increment tincr may be specified.

dim1 and dim2 are standard GrADS dimension expressions whose dimensions must match.

Usage Notes

  1. The limits and intervals of the summing are set according to the grid coordinates of the default file. If dim1 and dim2 are specified in world coordinates, the coordinates are converted to the nearest integer grid coordinates based on the scaling of the default file.

  2. The end points are given normal weighting, unless the -b boundary flag is specified. The boundry flag indicates that the sum should be taken to the exact boundaries specified by dim1 and dim2, rather than the nearest grid points.

  3. In the Y dimension, when the boundary is beyond the pole, the asum function recognizes this and weights appropriately. To calculate an sum without any weighting, use the sumg function.