MATLAB: Not enough input arguments error given

Question

I am given the error

Not enough input arguments.

Error in fun (line 2) f = cos(2*x)./exp(x);

When trying to run my code with the command

simp(fun, 0, 2*pi, 120)

for my code

function I = simp(fun, a,b,n)

%Standard simpson's rule 
tol = 0.0001;

h = (b-a)/(2*n); % The subinterval spacing
x = a:h:b; % The partition points
y = fun(x); % The function values at those points
i = 0:2*n; % Makes a list from 0 to 2*n

coeffs = 3+(-1).^(i+1); % Makes a list of 2s and 4s to use in the Simpson's Rule
coeffs(1) = 1; coeffs(end)=1;

SR = h/3 * sum(coeffs .* y); % This is the Simpson's Rule
disp(SR);

function f = fun(x)
f = cos(2*x)./exp(x);
end

The error is telling me that I did not provide enough input arguments, but I see that I give the function (fun), 'a', 'b', and 'n' values. So why am I getting this error?

TwistedSim · Accepted Answer · 2018-05-04 18:23:00Z

2

You need to pass the function handle with @:

simp(@fun, 0, 2*pi, 120)

You can also use:

simp(@(x) cos(2*x)./exp(x), 0, 2*pi, 120)

When you use only fun, Matlab think you try to call the function with no parameter. @fun is the actual function.

answered May 4, 2018 at 18:23

TwistedSim

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5 Comments

Taln Over a year ago

Hi Twisted, thank you for the answer. Why must I use the anonymous function handle?

TwistedSim Over a year ago

Function handle let you do things like: f = @myfunction, or f = @(x) anotherfunction(x).

Taln Over a year ago

Hm, okay. I'll just have to read more documentation regarding it. Thank you for your time!

TwistedSim Over a year ago

it's just a reference to the function instead of the actual function :) Take a look at this: mathworks.com/help/matlab/matlab_prog/…

Cris Luengo Over a year ago

@Taln : fun is the same as fun(). @fun is a function handle to fun. It’s not an anonymous function. An anonymous function would be the second case (@(x)...), where you define a new function without a name and get its handle.

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