Using fzero function to solve a nonlinear function with two inputs
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Hi,
My aim is to solve a non-linear equation for alpha with given values of X and al (both ranges of values). But I keep getting errors. Here is the code,
INPUTS:
function [n, m, Z] = setglblch
n=1 ;
m=1 ;
Z=14;
end
function [D, A, R] = geom()
D = 0.3; %Pipe Diameter (m)
R = D/2; %Pipe Radius (m)
A = pi*(R^2); %Cross-sectional Area (m^2)
end
function [X] = setX
X=linspace(0,100,101) ;
end
function [al] = setal
al=linspace(0,1,101) ;
end
SOLVING:
function y = equationsch(alpha, X, A, m, n, Z, al)
beta1 = (1-al).^(-1) ;
beta2 = al/((1/A)-al) ;
beta3 = 1/alpha ;
beta4 = beta1-beta2.*beta3 ;
beta = beta4.^(-1) ;
if X == 0
y = 0;
else
y1 = al.^(1-0.5) ;
y2 = (1-al).^(0.5*m-1) ;
y3 = X/Z ;
y4 = beta.^(1+m) ;
y5 = alpha.^(1+n) ;
y6 = (y4/y5).*y3 ;
y = y1.*y2-y6 ;
end
end
WITH ONE INPUT X:
function [alpha] = getalphach
[A] = geom();
[n, m, Z] = setglblch();
X = setX();
al = setal();
alpha = arrayfun( @(x) fzero( @(alpha) equationsch(angle, X, D, A, R, m, n, Z, al), [1E-4, pi-1E-4]), X );
end
I GET ERROR Not enough input arguments.
AND WITH TWO INPUTS X AND al:
function [alpha] = getalphach
[A] = geom();
[n, m, Z] = setglblch();
X = setX();
al = setal();
alpha = arrayfun( @(x) fzero( @(alpha) equationsch(angle, X, D, A, R, m, n, Z, al), [1E-4, pi-1E-4]), X, al );
end
I GET ERROR Too many input arguments.
How can this be fixed?
Any help truly appreciated!
0 Comments
Accepted Answer
Star Strider
on 16 Mar 2017
You need to change the argument from ‘alpha’ to ‘angle’ in the argument list for ‘equationch’.
With that change, it becomes:
alpha = arrayfun( @(x) fzero( @(angle) equationsch(angle, X, D, A, R, m, n, Z, al), [1E-4, pi-1E-4]), X, al );
I did not run your code, but that should resolve at least that problem.
3 Comments
Star Strider
on 16 Mar 2017
My pleasure!
Note that in your function definition:
function y = equationsch(alpha, X, A, m, n, Z, al)
‘equationsch’ has 7 arguments.
In this line:
alpha = arrayfun( @(x) fzero( @(angle) equationsch(angle, X, D, A, R, m, n, Z, al), [1E-4, pi-1E-4]), X, al );
you are passing it 9 arguments. That is likely what is throwing the error.
More Answers (1)
Egle
on 17 Mar 2017
4 Comments
Star Strider
on 17 Mar 2017
My pleasure.
It does help. The arrayfun function may not be able to do that.
I noticed that Torsten posted workable code that will do what you want (with a double loop) in your other related question. Torsten’s is probably the only workable solution.
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