Gri Commands
|
12.9: The `
|
`differentiate {x|y wrt index|y|x} | {grid wrt x|y}' |
Differentiate column data or grid data. Only the `x
' and `y
'
columns may be differentiated. They may be differentiated either with
respect to (``wrt'') the index (forming a first difference) or with
respect to the other column. The derivative is done with the
backwards-difference algorithm. Grid data may differentiated with
respect to `x
' direction or `y
' direction. Grid
differentiation is done with a centred difference, with endpoints being
assigned the derivative of the neighboring interior point (so that the
second derivative is zero at the edges of the grid).