Trying to use function ,didnt work?

function [Delta]= finddeflexion(Length)
E= 4.2*(10.^10);
I = 1*(10.^-5);
W = 8500;
prompt = "What is the length of the blade? ";
Length = input(prompt); 
Delta = W*(Length^3)/(8*E*I);

when i typed it like this it gave me error sayin to type the function part like so and i dont understand why

function [Delta]= finddeflexion(~)

the code then works fine

[Mann Baidi]

Why are you having "Length" as function parameter?

[Bastian]

not sure what you mean by function parameter

Answer 1

[Matt J]

when i typed it like this it gave me error

I doubt it gave you an error. It certainly doesn't give me one.

You probably got a Code Analyzer warning saying that the input argument "Length" is not being used. If you want it to be used remove the line which overwrites it:

function [Delta]= finddeflexion(Length)
    E= 4.2*(10.^10);
    I = 1*(10.^-5);
    W = 8500;
    prompt = "What is the length of the blade? ";
    %Length = input(prompt); 
    Delta = W*(Length^3)/(8*E*I);
end

[Bastian]

still dosent work wont let me input length which i am trying to do for quite some time

finddeflexion(length)

Error using length

Not enough input arguments.

[Bastian]

if instead of e I and w i use the actual values in the equation it worked once but then same error

[Matt J]

You have a lower case 'L' in length.

[Matt J]

finddeflexion(10)  %it works

ans = 2.5298

function [Delta]= finddeflexion(Length)
    E= 4.2*(10.^10);
    I = 1*(10.^-5);
    W = 8500;
    prompt = "What is the length of the blade? ";
    %Length = input(prompt); 
    Delta = W*(Length^3)/(8*E*I);
end

[Bastian]

finddeflexion(Length)

Unrecognized function or variable 'Length'.

Did you mean:

>> finddeflexion(length)

Error using length

Not enough input arguments.

[Matt J]

Either version is fine, but you should not be passing variables that haven't been assigned values to the function.

Length=10;
Delta = finddeflexion(Length)  %it works

Delta = 2.5298

length=5;
Delta = finddeflexion(length)  %it works - but Matlab's builtin length command is now unavailable

Delta = 0.3162

function [Delta]= finddeflexion(Length)
    E= 4.2*(10.^10);
    I = 1*(10.^-5);
    W = 8500;
    prompt = "What is the length of the blade? ";
    %Length = input(prompt); 
    Delta = W*(Length^3)/(8*E*I);
end

[Bastian]

iam trying to run it as a script and that is when it doesn't seem to be working for me. i thought if i hit run it wourld display [Delta]= finddeflexion(Length) but when i check options it says i can change what is in (length) to the value i want to put in but it wont let it run (length)

[Matt J]

In my last post, I ran it for you as a script. That is why you can see the output. If you put what I coded above in a script and hit Run, with no additional options, it will work.

[Bastian]

if you look at these images you will understand what i am trying to say

i want it s when i run it it displays as so

[Delta]= finddeflexion(Length)

and then let me the user type in the value for length

in first screen shot i have underlined what i mean by options when running, it seems that i have to put in value first like so, instead of just pressing run and changing the value of length in command window

[Matt J]

instead of just pressing run and changing the value of length in command window

Yes, we removed the line where you are prompted for the Length from the command window.

If you want to set the Length variable in the command window, then you should put that line back in, but remove "Length" from the function signautre line

function [Delta]= finddeflexion()  %or finddeflexion(~)
    E= 4.2*(10.^10);
    I = 1*(10.^-5);
    W = 8500;
    prompt = "What is the length of the blade? ";
    Length = input(prompt);   %<--- put this line back in
    Delta = W*(Length^3)/(8*E*I);
end