if statements, keep getting error can someone explain why?

Promt - Write a user-defined function named Deflection_cougarnetID.m which has one input (position x) and one output, (deflection v). You will need to apply the deflection equation above with the piecewise conditions described. Use this function to determine the deflection at the position entered. Produce a formatted output to the command window that states the deflection at the point entered.

code

script- %%

choose_in = input('Please enter a psoition between 0 and 360  ');
if (choose_in < 0)
     choose_in = abs(choose_in);
    Warning('You entered a negative value, taking the ablsolute value');
   
end

if (choose_in > 360)
    error('The value is greater than 360 inches, program terminated')
end

Deflection = Deflection_ahdoan2(choose_in)

function -

function [Deflection] = Deflection_ahdoan2(choose_in)
%DEFLECTION_AHDOAN2 Summary of this function goes here
%   Detailed explanation goes here
if  (0<choose_in<120);
    first = (choose_in);
    if (120<choose_in<240)
    second = (choose_in-120)
else 
    second = 0 
    if 
  (240<choose_in<360)
  third = (choose_in-240)
else 
    third = 0
 
       
    end
    end
end
def_form = (1/3.19*10^9)*(800*choose_in^3)-(13.68*10^6*choose_in)- (2.5*choose_in^4) + 2.5*(second)^4 + 600*third^3))
    
end  

[Adam Danz]

One of the reasons it's difficult to see the error is because your code is not properly indented. Open this file in matlab's editor, select all of the code (ctrl + a) and smart-indent (ctrl+i).

Answer 1

[Adam Danz]

if you open this file in the editor you'll see red markings indicating the lines that contains an error. The orange lines indicate potential improvements.

When you run the code, the error message tells you the line that contains the error and what the problem is. The error message in r2019b is

Error: File: xxxxxx.m Line: ## Column: ##
Invalid expression. Check for missing or extra characters.

Check out the examples of if-statements in the documentation and you'll see how your code differs from the examples. It's an easy fix.

https://www.mathworks.com/help/matlab/ref/if.html#bt7zco5-4

[Alex Doan]

i fixed it it still is running error

function [Deflection] = Deflection_ahdoan2(choose_in)

%DEFLECTION_AHDOAN2 Summary of this function goes here

% Detailed explanation goes here

if ((0<choose_in)<120));

first = (choose_in);

if ((120<choose_in)<240))

second = (choose_in-120)

else

second = 0

if (240<choose_in<360);

third = ((choose_in)-240))

else

third = 0;

end

end

end

def_form = ((1/3.19*10^9)*(800*choose_in^3)-(13.68*10^6*choose_in)-(2.5*choose_in^4) + 2.5*(second)^4 + 600*third^3))

end

[Adam Danz]

Please supply the full copy-pasted error message (all of it).

[Walter Roberson]

You fixed it incorrectly. We were telling you how matlab was interpreting your existing code, pointing out how it was wrong. You need to rewrite the form

A<X<B

as

   A<X && X<B

Answer 2

[Walter Roberson]

if  (0<choose_in<120);

In MATLAB, that means

    if  ((0<choose_in)<120);

0<choose_in is going to be 0 (false) or 1 (true). Then both 0 and 1 are < 120, so this statement would always be true.

[Alex Doan]

i did that it still give me an error