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From: "Muhamad " <madz_doank@yahoo.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Newton-Raphson
Date: Thu, 8 Apr 2010 23:03:05 +0000 (UTC)
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Walter Roberson <roberson@hushmail.com> wrote in message <hpllok$hac$1@canopus.cc.umanitoba.ca>...
> Muhamad wrote:
> 
> > %func_prime.m
> > 
> > function [value] = func_prime(x)
> > value = sin(A)-(sin(teta)*e^(-(180+A-teta)/WRC);
> > 
> > x = 1;
> > 
> > for j = 1:10
> >    x = x - func(x)/func_prime(x);
> > end
> 
> When you have a function, the only values that are returned to the calling 
> routine are the ones named before the '=' on the 'function' line. In this 
> code, 'value' is the only variable named there. Once you have computed value, 
> there is no point in doing any further work (unless it has to with graphics or 
>   outputs to a file or the display), because whatever you do will just be 
> thrown away. Thus the 'for' loop is not contributing anything to this routine 
> and can be discarded, just as the assignment to 'x' can be.
> 
> When you have a function, the only values that you can use in the function are 
> numeric constants, named constants such as pi, values you have already 
> computed in the routine, and values that you have named after the '(' on the 
> 'function' line. [I'm simplifying slightly; there are some more advanced 
> facilities.] You name x in that position, but you do not use x. You do, 
> though, attempt to use A, teta, and WRC, none of which fall into the 
> categories I describe. Thus A, teta, and WRC are undefined as far as this 
> routine is concerned. If you want to use the values that you input from the 
> user, then you need to give names for them on the 'function' line, and you 
> need to pass the values in when you call the routine. For example, you could call
> 
> func_prime(A, WRC, teta)
> 
> and your corresponding 'function' line would be
> 
> function value = func_prime(A, WRC, teta)

why but still error ?
------
??? Input argument 'teta' is undefined.

Error in ==> C:\Documents and Settings\madz\My Documents\Downloads\elda\func.m
On line 4  ==> f = cos(A)-sin(teta)*e^(-(180+A-teta)/W*R);

Error in ==> C:\Documents and Settings\madz\My Documents\Downloads\elda\Newton_Raphson.m
On line 11  ==> while (iterations<30) & (abs(func(x))>tolerance)
----