Hi, On Sun, 20 Jan 2002, Bob McElrath wrote:
[...]
What I see as needed in order to write some simplification routines are methods for the ex class like there are in the numeric class: is_real, is_integer, operator<, etc... And an assume() functionality to create symbols that are reals, integers, etc.
The reason this has not been done is that we have absolutely no idea how to make it consistent.
Really? Maybe I haven't thought about it as much as you...
But it seems you'd need methods: is_real is_negative etc... for every function (sqrt, sum, sin, pow, ...), which could then query their arguments in the appropriate manner to determine the final result.
The trouble starts already with trivial expressions: If a>0 and b>0, then (a+b)>0. But (a-b) would have to return false, as would (b-a). This makes it already difficult for sums. Ternary logic would help a bit, here. :-) [...]
By nested root you mean something like: sqrt(a+sqrt(b)) right?
Yes. Regards -richy. -- Richard Kreckel <Richard.Kreckel@Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/>