# system of non linear functions

6 views (last 30 days)
Lucrezia Cester on 13 Dec 2019
Commented: Lucrezia Cester on 13 Dec 2019
Hello,
I get an error saying not enough input arguments.
I literally tried to go step by step from the matlab tutorial for non linear functions.
Do you know what might be wrong?
Thanks!
function F = root2d(x)
F(1) = 97-(1/sqrt(2))*(exp((1i)*(136)*x(1)))- exp((1i)*105*x(2))*(1/sqrt(2));
F(2) = 51-(1/sqrt(2))*(exp((1i)*(51)*x(1)))- exp((1i)*14*x(2))*(1/sqrt(2));
fun = @root2d;
x0 = [0,0];
x = fsolve(fun,x0)
Star Strider on 13 Dec 2019
Your code runs for me without error:
function F = root2d(x)
F(1) = 97-(1/sqrt(2))*(exp((1i)*(136)*x(1)))- exp((1i)*105*x(2))*(1/sqrt(2));
F(2) = 51-(1/sqrt(2))*(exp((1i)*(51)*x(1)))- exp((1i)*14*x(2))*(1/sqrt(2));
end
fun = @root2d;
x0 = [0,0];
x = fsolve(fun,x0)
(I added an end to the function because I am running it inside another function I use to test Answers functions.)
It produces a normal termination for fsolve, and these parameter estimates:
x =
0.000514467767515 - 0.082745912708573i -0.029252385734369 - 0.107158749735724i

Steven Lord on 13 Dec 2019
It's unclear from what you've posted whether the last three lines of your code:
fun = @root2d;
x0 = [0,0];
x = fsolve(fun,x0)
are inside root2d.m or outside. They need to be outside of root2d.m, otherwise you will either receive an error about not enough input arguments (if you call root2d with no input arguments) or (eventually) an error about the recursion limit or simply a crash (if you call root2d with an input argument that has at least two elements.)
Why would you receive the recursion limit error if you call this with an input argument?
Your first call to root2d would call fsolve
which would call root2d which would call fsolve
which would call root2d which would call fsolve
which would call root2d which would call fsolve ...
Break this infinite loop by not calling fsolve inside root2d to solve the system computed by root2d.
Lucrezia Cester on 13 Dec 2019
yup, thank you very much! that was the problem! the lines had to be outisde