From: Osman.Buyukisik@ae.ge.COM (U-E59264-Osman Buyukisik)
Newsgroups: sci.math.symbolic
Subject: Re: non-linear curve fitting.
Date: 3 Jul 96 04:01:33 GMT
>>>>> "skypak" == skypak writes:
skypak> Subject: non-linear curve fitting.
skypak> I NEED HELP IN DETERMINING THE CONSTANTS C1 THROUGH C4
skypak> FOR THE FOLLOWING EQUATION FOR A SET OF X AND Y
skypak> VALUES. THE EQUATION IS
skypak> AS FOLLOWS
skypak> log y = C1 SINH [C2(LOG X + C3)] + C4
skypak> THE TYPICAL VALUES OF X AND Y ARE
skypak> Y X (10E-6)
First : Don't use all caps!
Second : Get gnuplot 3.6 beta (check comp.graphics.apps.gnuplot). It has a "fit" function.
It is available for almost any platform. Here is what you may have to type:
f(x)=exp(c1*sinh(c2*log(x)+c3)+c4)
c1=1
c2=1
c3=1
c4=1
fit f(x) 'foo' via c1,c2,c3,c4
plot 'goo' title "data", f(x) title "fitted func"
And put your x,y data into the file 'foo', you'll get your answers.
You may have to give reasonable starting values intead of 1's.
Osman