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Thread Subject:
how to solve two unknowns in two complicated eqns

Subject: how to solve two unknowns in two complicated eqns

From: Yi

Date: 28 Apr, 2009 18:26:03

Message: 1 of 2

Dear matlab friends:

I have two very complicated eqns, like this:
x = f(x,y)
y = f'(x,y)
both f and f' are very very complocated,
for example f(x,y) = cosxy + siny +y/28*e^xy+ log(x/y^1.41)+....

I cannot use "solve" to solve it cause it seems take forever to get the solution.

How to write a code to solve these two eqns?

I wrote a fix-point iteration code to solve one unknown with one eqn. But I don't know how to write a code for several unknown variables.

Any suggestion is welcome.

Thanks & Best Regards

Yi

Subject: how to solve two unknowns in two complicated eqns

From: Feng

Date: 28 Apr, 2009 18:59:01

Message: 2 of 2

what do you mean 'very very complicated'?
the variables are x and y?
so you get eq1: f(x,y) - x = 0; eq2: f'(x,y) - y = 0;
if you just want to get the values of these two varialbes, try fsolve, give initial guess.


"Yi" <hvachy@163.com> wrote in message <gt7hnr$miq$1@fred.mathworks.com>...
> Dear matlab friends:
>
> I have two very complicated eqns, like this:
> x = f(x,y)
> y = f'(x,y)
> both f and f' are very very complocated,
> for example f(x,y) = cosxy + siny +y/28*e^xy+ log(x/y^1.41)+....
>
> I cannot use "solve" to solve it cause it seems take forever to get the solution.
>
> How to write a code to solve these two eqns?
>
> I wrote a fix-point iteration code to solve one unknown with one eqn. But I don't know how to write a code for several unknown variables.
>
> Any suggestion is welcome.
>
> Thanks & Best Regards
>
> Yi

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