To learn how to work with fzero() I tried this code:
function equation(x)
k=(96-x)/6;
end
and then:
x0=4;
x=fzero('equation',x0)
The error is:
??? Error using ==> fzero at 307
FZERO cannot continue because user supplied function_handle ==> equation
failed with the error below.
Too many output arguments.
fzerois expecting a return value from your equation so (internally) it is trying to assign something to the output of that function. If I try
result = equation(42);
I get the same error message
Error using equation
Too many output arguments.
Just change your function signature to
function [k] = equation(x)
to indicate that k is the output of this function.
Try to supply the function argument as handle:
x = fzero(#equation,x0)
Related
https://www.mathworks.com/help/optim/examples/banana-function-minimization.html
fun = #(x)(100*(x(2) - x(1)^2)^2 + (1 - x(1))^2);
options = optimset('OutputFcn',#bananaout,'Display','off');
x0 = [-1.9,2];
[x,fval,eflag,output] = fminsearch(fun,x0,options);
title 'Rosenbrock solution via fminsearch'
Fcount = output.funcCount;
disp(['Number of function evaluations for fminsearch was ',num2str(Fcount)])
disp(['Number of solver iterations for fminsearch was ',num2str(output.iterations)])
What is #bananaout here?
This is giving me the following error,
??? Error using ==> feval
Attempt to execute SCRIPT bananaout as a function:
C:\Users\admin\Desktop\bananaout.m
Error in ==> callAllOptimOutputFcns at 12
stop(i) = feval(OutputFcn{i},xOutputfcn,optimValues,state,varargin{:});
Error in ==> fminsearch>callOutputAndPlotFcns at 464
stop = callAllOptimOutputFcns(outputfcn,xOutputfcn,optimValues,state,varargin{:})
|| stop;
Error in ==> fminsearch at 199
[xOutputfcn, optimValues, stop] =
callOutputAndPlotFcns(outputfcn,plotfcns,v(:,1),xOutputfcn,'init',itercount, ...
Error in ==> test_optim at 9
[x,fval,eflag,output] = fminsearch(fun,x0,options)
As per the doc, Output Functions are called by the optimizer at every time step, enabling you to do things like plot the progress of the optimization.
In your case you get an error because bananaout seems to be a script when it needs to be a function (with specific inputs - see the doc for their details). Did you happen to save the example code in a script called bananaout? If so, rename the script.
You can see a list of all m-code that you have that are called bananaout by executing the following:
>> which bananaout -all
One of them will be the function that the example should be calling, while another will be the one that you have created and need to rename/remove.
Maybe i'm missing something obvious, but i'm just starting matlab so...
I have created many user defined function and use them to solve another function.
each function works when tested separately, but when I try test the bigger function, i get this message:
Error using F1 (line 2)
Not enough input arguments.
Error in run (line 5)
[X,Y]=NewrRaph2(F1,F2,d1x,d1y,d2x,d2y,1,1,iter)
my function F1 is:
function [F1]=F1(x,y)
F1=4*x^2+y^3+28;
and my function Newraph2 is:
function [X,Y]=NewrRaph2(F1,F2,d1x,d1y,d2x,d2y,x,y,iter)
x=x;
y=y;
for n=1:iter
deltax=((-F1(x,y)*d2y(y))+(F2(x,y)*d1y(y)))/Jacob(dix(x),d1y(y),d2x(x),d2y(y));
deltay=((-F2(x,y)*d1x(x))+(F1(x,y)*d2x(x)))/Jacob(d1x(x),d1y(y),d2x(x),d2y(y));
x=deltax+x;
y=deltay+y;
end
X=x;
Y=y;
also, to test my function I use this script:
clear, clc
x=input('valeur de x ')
y=input('valeur de y ')
iter=input('valeur de iter: ');
[X,Y]=NewrRaph2(F1,F2,d1x,d1y,d2x,d2y,x,y,iter)
But I don't understand what I did wrong.
I want to use an integral over a vector but I will see an error for sys_eff which is " First input argument is not function handle."
I will be glad to have your guide and thanks in advance.
I should mention that all vectors have the same ize as 345600.
function [ P_loss,time_eff, sys_eff ] = final( Pmpp, Pl_inv, Pl_bat_inv, Pl_bat_r )
j=length(Pmpp);
for t=1:j;
P_loss(t)= Pl_inv(t) + Pl_bat_inv(t) + Pl_bat_r(t);
time_eff(t)= P_loss(t)/Pmpp(t);
end
sys_eff=integral(time_eff,0,345600);
end
As from the error message, the first input you provided to the function integral (i.e. time_eff) is not a function handle, but a vector.
If you want to make a numeric integral of the function use the function trapz
sys_eff=trapz(t,time_eff)
if t is your integration variable.
I want to call a function in Matlab using another one, which has the same number of inputs and outputs. In fact, those inputs and outputs have the same name.
Example:
function [a,b] = gettwo(matrix,string,varargin)
[a,b] = getone(matrix,string,varargin{:});
end
This code produces the following error:
Error in getone(line 3)
aux = 'matrix(varargin{:})';
Output argument "b" (and maybe others) not assigned during
call to "C:\Users\baister\Documents\MATLAB\soft\getone.m>getone".
Error in results (line 4)
[a,b] = getone(matrix,string,varargin{:});
How should I wrap getone?
(The definitive function will have more lines than those shown in this post.)
Thanks.
The general wrapping for variable number of outputs should work like this:
function [varargout] = gettwo(matrix,string,varargin)
[varargout{1:nargout}] = getone(matrix,string,varargin{:});
end
You'll get the same error as above though, in case you do
[a,b] = gettwo(...);
and getone returns only 1 argument.
I created an anonymous function inside a script and I can't get MATLAB to run the fminsearch? Here's an what I have so far:
V=x(1);
f=x(2);
q=#(x) (pi.*D.*L)./(1000.*V.*f);
fminsearch(#q,x);
The variables D and L are defined, but MATLAB gives me the following error:
Error: File: Testing.m Line: 51 Column: 17
"q" was previously used as a variable, conflicting with its use here as the name of a function or command.
See "How MATLAB Recognizes Command Syntax" in the MATLAB documentation for details.
q is not mentioned before this command. What am I doing wrong?
Another thing that could solve my problem is to get my script to write a function file, but how to do that?
Remove the second #:
V=x(1);
f=x(2);
q=#(x) (pi.*D.*L)./(1000.*V.*f);
fminsearch(q,x);
q is a function handle. fminsearch expects a function handle. You can create a function handle out of a function using an # (e.g. #min), but you don't need to do that here.
You can also write the anonymous function inline with the search command:
V=x(1);
f=x(2);
fminsearch(#(x) (pi.*D.*L)./(1000.*V.*f),x);
UPDATE (credits to #wakjah)
For your code to do anything sensible, you should use the argument x of the anonymous function:
x0 = [initialV, initialF];
fminsearch(#(x) (pi.*D.*L)./(1000.*x(1).*x(2)), x0);
#function creates a function handle for an existing function.
q = #(x) whatever... creates a function handle called q.
But, you can't create a function handle for a function handle, only for a function.
See this:
>> fones = #ones
fones =
#ones
>> ffones = #fones
Error: "fones" was previously used as a
variable,
conflicting with its use here as the name
of a function or command.
See MATLAB Programming, "How MATLAB
Recognizes Function Calls That Use
Command Syntax" for details.
In Matlab, a function handle is a kind of a pointer to a function and is distinct from a function (unlike in some other languages where the a function identifier can be passed and stored as any other variable).
It's important to note that calling a function and a function handle results in the same behaviour. Except for the case where the identifier is used without any parentheses following it:
>> ones
ans =
1
>> fones
fones =
#ones
>> ones(2)
ans =
1 1
1 1
>> fones(2)
ans =
1 1
1 1