On Mon, Feb 7, 2011 at 22:19, Barry Smith <[email protected]> wrote:

It uses U0 but never explains what it is. It also calls a the "shift" but never explains what it is. Perhaps some notes explaining this stuff would make the solver more transparent. And a reference to further material that uses this approach would be great if it exists.

Suppose we have f(x,y). There are two ways to express the derivative we need 1. f_x(x,y) + a*f_y(x,y) 2. g_x where g(x) = f(x,z+a*x) I used version 2 in the man page because I think 1 looks arbitrary and is less obvious how it arises from a time integrator. There is a note later in the page about the equivalence. I suppose the name "shift" is more natural for version 1. Do you think I should make version 1 primary (or remove any mention of 2)? Do you have a better name for "shift", or just want more text (I felt like elaborating would be describing a simple equation in words)?