From help-request at octave dot org Sun Feb  6 17:57:01 2005
Subject: Re: two quadratic eq, please help
From: Geordie McBain <geordie dot mcbain at aeromech dot usyd dot edu dot au>
To: shih lin <shlinlin at 37 dot com>
Cc: help at octave dot org
Date: Mon, 7 Feb 2005 09:46:54 -0500

On Sun, Feb 06, 2005 at 12:25:18AM -0800, shih lin wrote:
> dear octave and math programmers:
> 
>   highly appreciate anyone can tell me how (or hint) to use octave to 
> solve:(12-x)^2 + y^2 =15^2, (16+y)^2+x^2=25^2 (by programming or using its built 
> in function)?
> that ^2 mean square.
> looking to any math&programer's help,
>  eric, fsshl at yahoo dot com

Create a function to return the residual:

  function z = f (x)
    z = [(12-x(1))^2+x(2)^2-15^2, (16+x(2))^2+x(1)^2-25^2];
  endfunction

and fsolve it:

octave> fsolve ("f", [0, 0])
ans =

   1.8887e-15
   9.0000e+00

Geordie McBain
www.aeromech.usyd.edu.au/~mcbain



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