Not enough input arguments (line 2)

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meman4567
meman4567 2023-1-24
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
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
end
FOR LOOP:
printstuff(nonsense,[4 11 15 20])
for x = [4 11 15 20]
nonsense(x);
end
  1 个评论
Stephen23
Stephen23 2023-1-24
编辑：Stephen23 2023-1-24
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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采纳的回答

Stephen23
Stephen23 2023-1-24
编辑：Stephen23 2023-1-24
Ran in:
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
  2 个评论
meman4567
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?

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更多回答（1 个）

Arif Hoq
Arif Hoq 2023-1-24
Ran in:
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
  2 个评论
meman4567
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
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
Arif Hoq 2023-1-24
Ran in:
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

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