# A function without any argument

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Wissem-Eddine KHATLA am 5 Apr. 2022
Kommentiert: Voss am 5 Apr. 2022
Hello everyone,
Could someone help me to understand why I got this error while running my script :
>> shoot4nl
Not enough input arguments.
My script is the following :
function shoot4nl
% Shooting method for nonlinear 4th-order boundary
% value problem
global XSTART XSTOP H % Make these params. global.
XSTART = 0; XSTOP = 1; % Range of integration.
H = 0.1; % Step size.
freq = 1; % Frequency of printout.
u = [-1 1]; % Trial values of u(1)
% and u(2).
x = XSTART;
u = newtonRaphson2(@residual,u);
[xSol,ySol] = runKut5(@dEqs,x,inCond(u),XSTOP,H);
printSol(xSol,ySol,freq)
function F = dEqs(x,y) % Differential equations.
F = zeros(1,4);
F(1) = y(2); F(2) = y(3); F(3) = y(4);
if x < 10.0e-4; F(4) = -12*y(2)*y(1)^2;
else; F(4) = -4*(y(1)^3)/x;
end
function y = inCond(u) % Initial conditions; u(1)
y = [0 0 u(1) u(2)]; % and u(2) are unknowns.
function r = residual(u) % Bounday residuals.
global XSTART XSTOP H
r = zeros(length(u),1);
x = XSTART;
[xSol,ySol] = runKut5(@dEqs,x,inCond(u),XSTOP,H);
lastRow = size(ySol,1);
r(1) = ySol(lastRow,3);
r(2) = ySol(lastRow,4) - 1;
I am trying to implement a shooting method algorithm for solving a non-linear equation.
Best regards.
##### 7 Kommentare5 ältere Kommentare anzeigen5 ältere Kommentare ausblenden
Wissem-Eddine KHATLA am 5 Apr. 2022
@Torsten@Jan This is the complete error obtained :
>> shoot4nl
Not enough input arguments.
Error in runKut5 (line 53)
if e <= eTol
Error in shoot4nl>residual (line 34)
[xSol,ySol] = runKut5(@dEqs,x,inCond(u),XSTOP,H);
Error in newtonRaphson2>jacobian (line 35)
f0 = feval(func,x);
Error in newtonRaphson2 (line 19)
[jac,f0] = jacobian(func,x);
Error in shoot4nl (line 14)
u = newtonRaphson2(@residual,u);
I wille edit my post to share the other functions in order to run properly what I wrote.
Thanks
Jan am 5 Apr. 2022
Bearbeitet: Jan am 5 Apr. 2022
Fine. This is useful. The problem occurs inside "runKut5". Most likely this function expects more inputs, than you provide in:
[xSol,ySol] = runKut5(@dEqs,x,inCond(u),XSTOP,H);
Please post the code of the failing function. What is "e" and "eTol"?

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### Akzeptierte Antwort

Voss am 5 Apr. 2022
There is a line in runKut5 that looks like it accidentally got commented out due to a comment on the previous line:
if nargin < 6; eTol = 1.0e-6; end
This line sets eTol to 1e-6 if it is not given as an input argument (it is the 6th input). Your calling function calls runKut5 with 5 inputs, so making this change should avoid the error. Updated runKut5.m is attached here.
##### 2 KommentareKeine anzeigenKeine ausblenden
Wissem-Eddine KHATLA am 5 Apr. 2022
@_ Thank you for your help : it worked now. I didn't pay attention to this line : thanks !
Voss am 5 Apr. 2022
You're welcome!

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