Not enough input arguments (line 2)

Question

meman4567 2023-1-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1899380-not-enough-input-arguments-line-2

评论： Stephen23 2023-1-24

Using the two functions I have defined so far (nonsense and printstuff) to run the for loop at the end. When running the for loop, it turns me back to the nonsense .m file and says 'not enough input arguments' (line2). Can anyone help with this?

NONSENSE:

function y=nonsense(x)

if mod(x,2) == 0

disp(x^2);

else

disp(0);

end

PRINTSTUFF:

function printstuff(func,values)

fprintf('Function evaluated at %d points: \n',length(values))

for q = 1:length(values)

fprintf('point %0.6f has value %0.6f\n',values(q),func(values(q)))

end

FOR LOOP:

printstuff(nonsense,[4 11 15 20])

for x = [4 11 15 20]

nonsense(x);

end

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Stephen23 2023-1-24

编辑：Stephen23 2023-1-24

在 MATLAB Online 中打开

The function NONSENSE requires one input argument when it is called.

Here you are calling NONSENSE with zero input arguments:

printstuff(nonsense,[4 11 15 20])
%          ^^^^^^^^ calling with zero input arguments.

What do you expect that to achieve? It seems that you need to use a function handle.

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Answer 1

Stephen23 2023-1-24

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1899380-not-enough-input-arguments-line-2#answer_1154965

编辑：Stephen23 2023-1-24

在 MATLAB Online 中打开

You need to learn about function handles:

https://www.mathworks.com/help/matlab/function-handles.html

I also had to fix your code because you had not defined the output argument "y" inside NONSENSE().

%          v                       !!! define function handle !!!
printstuff(@nonsense,[4,11,15,20])
Function evaluated at 4 points: 
point 4.000000 has value 16.000000
point 11.000000 has value 0.000000
point 15.000000 has value 0.000000
point 20.000000 has value 400.000000
function y = nonsense(x)
if mod(x,2) == 0
    y = x^2;
else
    y = 0;
end
end
function printstuff(func,values)
fprintf('Function evaluated at %d points: \n',length(values))
for q = 1:length(values)
    fprintf('point %0.6f has value %0.6f\n',values(q),func(values(q)))
end
end

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meman4567 2023-1-24

Thanks for your answer. The ampersand did the trick (defining the function handle?)

Will definitely spend some time looking at the function handles: i'm very new to matlab so the more info I can take in the better :)

Not sure if info on this is in the documentation, but what exactly does the @ do?

Stephen23 2023-1-24

"Not sure if info on this is in the documentation, but what exactly does the @ do?"

https://www.mathworks.com/help/matlab/function-handles.html

https://www.mathworks.com/help/matlab/matlab_prog/creating-a-function-handle.html

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Answer 2

Arif Hoq 2023-1-24

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1899380-not-enough-input-arguments-line-2#answer_1154930

在 MATLAB Online 中打开

x=12:10:42;
out=nonsense(x);
         144         484        1024        1764
function y=nonsense(x)
if mod(x,2) == 0
    y=x.^2;
else
    y=0;
end
disp(y)
end

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meman4567 2023-1-24

Thanks for your answer. That code runs just fine. Now, I am using the following function

function printstuff(func,values)

fprintf('Function evaluated at %d points: \n',length(values))

for q = 1:length(values)

fprintf('point %0.6f has value %0.6f\n',values(q),func(values(q)))

end

Then using the two functions I have defined so far (nonsense and printstuff) to run this. This is where it turns me back to 'not enough input arguments'

printstuff(nonsense,[4 11 15 20])

for x = [4 11 15 20]

nonsense(x);

end

Arif Hoq 2023-1-24

在 MATLAB Online 中打开

You can do it with a single function.

x = [4 11 15 20];
% x=[4 8 12 16 20];
out=nonsense(x);
Function evaluated at 4 points: 
point 4.000000 has value 16.000000
point 11.000000 has no value 0.000000
point 15.000000 has no value 0.000000
point 20.000000 has value 400.000000
function y=nonsense(x)
fprintf('Function evaluated at %d points: \n',length(x))
for i=1:length(x)
if mod(x(i),2) == 0
    y=x(i).^2;
    fprintf('point %0.6f has value %0.6f\n',x(i),y)
else
    y=0;
    fprintf('point %0.6f has no value %0.6f\n',x(i),y)
end
end
end