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From: "Steven_Lord" <slord@mathworks.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Adams-Bashforth-Moulton method
Date: Tue, 5 Feb 2013 13:12:32 -0500
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"Emilia Przybysz" <emilia.przybysz0909@gmail.com> wrote in message 
news:46eeeba3-e22b-4db4-8726-6cb19b69a47d@googlegroups.com...
> Hi, I have a huge problem. I have to write a script that solve 
> differential equation like this
> 2000y"=98(1+y')^2{t(t-1)+2}
> using Adams-Bashforth-Moulton method and then compare results using ode45. 
> I wrote a function
>
>>function dy = belka(t,y)
>>% funkcja w ktrej zapisali?my rwnanie rniczkowe
>>dy=zeros(2,1) ;
>>dy(1)=y(2);
>>dy(2)=(9.8*10/2000)*(1+y(2))^2*{t.*(t-1)+2};

The section:

{t.*(t-1)+2}

creates a cell array. MATLAB doesn't know how to multiply the previous term 
in the definition for dy(2):

(9.8*10/2000)*(1+y(2))^2

and a cell array -- it's not defined. Use parentheses instead of curly 
braces if all you want to do is group together the expression representing 
"t times t-1, plus 2", just like you used parentheses to group the 
expression "9.8 times 10 divided by 2000."

*snip*

>>[t, y]=rk4(f, tspan0, y0, 3, varargin{:});

Here and in the similar function evaluation calls later in your code curly 
braces ARE needed, as you're working with the cell array VARARGIN.

*snip*

-- 
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on 
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