cal/cal/root.cal

{ RCSid $Id$ }
{
        root.cal - calculate zeroes of functions using Newton's method.

        2/3/88
}

FTINY : 1e-12;

root(f, x0) = root2(f, x0, x0-f(x0)/lim(f1(f,x0)), nit);

root2(f, x0, x1, i) = if(i,
                        if(err-abs(x1-x0),
                                x1,
                                root2(f,x1,x1-f(x1)/lim(f1(f,x1)),i-1)),
                        0);

abs(x) = if(x, x, -x);
lim(x) = if(x, max(x,err), -max(-x,err));
max(a,b) = if(a-b, a, b);

f1(f,x) = (f(x+FTINY)-f(x-FTINY))/(2*FTINY);    { numerical derivative }

err = 1e-6;
nit = 100;
Revision:	1.2
Committed:	Sat Sep 4 19:26:09 2010 UTC (13 years, 8 months ago) by greg
Branch:	MAIN
Changes since 1.1:	+2 -1 lines
Log Message:	Minor updates
#	User	Rev	Content
1	greg	1.2	{ RCSid $Id$ }
2	greg	1.1	{
3			root.cal - calculate zeroes of functions using Newton's method.
4
5			2/3/88
6			}
7
8			FTINY : 1e-12;
9
10			root(f, x0) = root2(f, x0, x0-f(x0)/lim(f1(f,x0)), nit);
11
12			root2(f, x0, x1, i) = if(i,
13			if(err-abs(x1-x0),
14			x1,
15			root2(f,x1,x1-f(x1)/lim(f1(f,x1)),i-1)),
16			0);
17
18			abs(x) = if(x, x, -x);
19			lim(x) = if(x, max(x,err), -max(-x,err));
20			max(a,b) = if(a-b, a, b);
21
22	greg	1.2	f1(f,x) = (f(x+FTINY)-f(x-FTINY))/(2*FTINY); { numerical derivative }
23	greg	1.1
24			err = 1e-6;
25			nit = 100;