Not sure what's wrong with my code

Having trouble calling the function altidense,

Whenever i try calling the function with the command "altidense(1500) i get a "Undefined function 'altidens' for input arguments of type 'double'"

I've been tearing my hair out because the code in the function itself is fine i tried by just inputting altitude directly and it worked fine. Its just when i call it as a function that makes the code fail.

Thanks

AltVsDens = readmatrix('Rho_ISA.csv');
altidense(1500)
%function to find air density from Rho_ISA.csv
%takes altitude and extracts air density from neighbouring cell
function airp = altidense(Altitude)
    cell = (Altitude/500)+1;
    airp = AltVsDens(cell,2)
end
%function to calculate true airspeed
%where m = mass, p = air density, s = wing area, Cl = coefficient of lift
function V = truspeed(m,p,s,Cl)
    V = sqrt((2*m*9.81)/(p*s*Cl))
end

[Johan]

You can't call a variable that is not part of a function in a function.

I would suggest adding your AltVsDens variable as an input to your function.

AltVsDens = readmatrix('Rho_ISA.csv');
altidense(1500,AltVsDens)
%function to find air density from Rho_ISA.csv
%takes altitude and extracts air density from neighbouring cell
function airp = altidense(Altitude,data)
    cell = (Altitude/500)+1;
    airp = data(cell,2)
end

[William Xupravati]

Thanks,

Do you know where i can read up more on this? because i dont fully understand why and how this works.

[Cris LaPierre]

It boils down to variable scope. Consider the following links

• Base and Fucntion Workspaces
• What are variable scopes?

Answer 1

[Jan]

The providing of variables as inputs and outputs as well as sharing the data using nested cells is explained in the free online tutorial: https://www.mathworks.com/learn/tutorials/matlab-onramp.html