Loading a file into a function error: "Unable to resolve the name __"

I am trying to create a function that uses data from a file named Atmos.mat, however, no matter how I load the file, the function returns the error: "Unable to resolve the name Atmos.mat" Any help would be greatly appreciated :)

function x = rho(point)
load('Atmos.mat')
distance = zeros(1,229);
for k = 1:1:229
    distance(k) = abs(point - Atmos.Hm(k));
end
for k = 1:1:229
    if (distance(k) == min(distance))
        break
    end
end

x0 = Atmos.Hm(k);
p = @(x) (x - x0)/(Atmos.Hm(2) - Atmos.Hm(1)); 
f =  @(x) p(x)*(p(x)-1)/2;
interpolation = @(x) Atmos.rhosi(k) + p(x)*(Atmos.rhosi(k + 1) - Atmos.rhosi(k))- f(x)*(Atmos.rhosi(k + 2) -2*Atmos.rhosi(k + 1)+ Atmos.rhosi(k));
x = interpolation(point)
end

[Jonas]

does the error occur in the load() line or in the line you use the variable Atmos first? We don't know if your file Atmos.mat contains the variable Atmos

[Michal Amar]

The error occurs in my first use of the variable Atmos.Hm (column entitled Hm within the Atmos file)

Answer 1

[Cris LaPierre]

You have given two different errors.

"Unable to resolve the name Atmos.mat"

Check that Atmos.mat is either in your current folder when you call your function, or in a folder that is on your MATLAB path.

"The error occurs in my first use of the variable Atmos.Hm"

Check that your mat file contains a table or structure Atmos with a variable or fieldname Hm.

[Michal Amar]

How do I do that?

[Cris LaPierre]

See this page for precedence.

For the 2nd error, in MATLAB, do the following

clear
load Atmos.mat

Check your workspace for a variable Atmos. Double click on it to open it in the Variable Editor to inspect its contents.

[Michal Amar]

I did that and now receive the error: "Reference to a cleared variable point."

[Cris LaPierre]

I'm afraid that is not enough context for me to interpret. When sharing an error message, share all the red text. Better still, attach your mat file to your post so we can run and test your code. You can use the paperclip icon to attach files.

[Michal Amar]

>> rho

Reference to a cleared variable point.

Error in rho (line 7)

distance(k) = abs(point - Atmos.Hm(k));

Attached I added the rho.m function and the Atmos file

[Cris LaPierre]

And how do you call your function (what is your input point)?

[Michal Amar]

the input point is just a number. this function is simply called to find the linear interpolation about a certain point. so I would call it as rho(1000) to find the aproximated value of rho at 100 meters, according to the Atmos data set

[Cris LaPierre]

Ok, thanks. Keep in mind that rho is a function that expects an input. You should always call it with an input.

In the function you have attached, you have added a clear to the top of your function. This is clearning your input variable. I see my early suggestion confused you. I wanted you to run that code in your Command Window, not add it to your function. Because you named your input variable points inside the function, and because you have a clear at the top of the function, you are getting this error.

>> rho(1000)

Reference to a cleared variable point.

Error in rho (line 7)
    distance(k) = abs(point - Atmos.Hm(k));

Remove the clear from line 2.

When I inspect your mat file, I see it contains a table named Atmos1 instead of Atmos. Update your function to use the correct variable name, and as long as your function can access the mat file, your function should work.

[Michal Amar]

Thank you thank you thank you!

You are an absolute life saver. Thank you for taking the time to walk me through this problem!