From kde-core-devel  Wed Nov 17 22:47:41 1999
From: Cristian Tibirna <ctibirna () total ! net>
Date: Wed, 17 Nov 1999 22:47:41 +0000
To: kde-core-devel
Subject: Re: Need help for KSpread Maths
X-MARC-Message: https://marc.info/?l=kde-core-devel&m=94287884622995


On Wed, 17 Nov 1999, weis wrote:

> Hi,
> 
> Excel has this "Goal Seek". Nice thing. You point it to a formular
> and to the cell that is used as input and Excel finds the
> input value that makes the formula result in a user specified value.
> 
> In fact that is the problem of finding x in f(x) = 0.
> 
> There are many algorithms which help you here, but they want
> a) a range [a,b] to search in which can be very big with double values.
> b) two points a and b, so that f(a)*f(b) < 0.
> 
> Can anyone tell me what to do here. Excel is getting quick and good
> results, so there must be a way.
> 
> Bye
> Torben
> 
> PS: No algebraic solutions.

Seems like this is a job for me.

Torben, is this pressing? I have to fix kikbd first, and work on kwin in
the meanwhile. But I'd really like to do this numeric kind of things since
this is my real-life job: numerical simulation. I believe for more general
situations a Simplex algorithm will do. 

If it is very important to avoid local optimums, we can look at Simulated
Anealing.

Of course, I'd better do this in kscripts and have them pluggable.

Does anybody know excel's Solver? It's highly used by engineers and I'm
sure we can do even better.

Cristian