XFOIL with MATLAB

[nikolhs]

hello azredwing,
First of all: yes i 'm using windows.
Secondly, i would be very interested in the scripts you told so when you finish them let us know...
Finally what you said before isn't clear to me...How can i supply input arguments to the function ? and one more...
what is the file " coeffs.txt " in the end of the .m file? is automatically created or should i create it ?if i have to create it what should i write in ?

[azredwing]

Hey azredwing,

I"m running Matlab 7.0 on window xp. and since i don't know Perl at all,
I also have ActivePerl 5.9.9 build 519 installed, but when i copied your
Perl code, i did it in notepad and save it as .pl

Do I need to update my matlab or anything?

Thanks in advance.

In a MATLAB prompt, run:

!perl -v

What is the output?

Since you've got ActivePerl installed, you could change MATLAB's PATH to use that Perl interpreter instead of the one built-in. Upgrade to ActivePerl 5.10, then follow the directions here:

http://home.online.no/~pjacklam/matlab/doc/perl/

[azredwing]

hello azredwing,
First of all: yes i 'm using windows.
Secondly, i would be very interested in the scripts you told so when you finish them let us know...
Finally what you said before isn't clear to me...How can i supply input arguments to the function ? and one more...
what is the file " coeffs.txt " in the end of the .m file? is automatically created or should i create it ?if i have to create it what should i write in ?

The code should be run like:

[CL, CD] = get_coeffs(alfa, Re, Ma, [NACA])

so say I want to analyze a NACA 0021 airfoil at 3.5 degrees AoA, with a Mach number of 0.05 and a Reynolds number of 500,000:

[CL, CD] = get_coeffs(3.5, 500000, 0.05, '0021')

(Note that you can figure this out if you read the comments in the m-file code!)

As for coeffs.txt: don't create it. The Perl script generates this file, but for some reason the interpreter that ships with MATLAB doesn't clean it up. I end up doing it in MATLAB instead of Perl (which isn't the nicest way to do it - and I'll be cleaning this up in my next version of the code.)

[nikolhs]

it's me again...
i have changed it :
function [CL,CD] = get_coeffs(1, 10000, 0.3, '0012')
but the line which incudes this gets red and it says:
invalid syntax at '1'.Possibly, a),}, or] is missing
parse error at ')':usage might be invalid MATLAB syntax
so when i run it appears: un expected matlab expression... do you know what have i done wrong (again)? the values 1,10000 etc only in this line need to replace alfa,Re etc... am i wrong ?

[azredwing]

it's me again...
i have changed it :
function [CL,CD] = get_coeffs(1, 10000, 0.3, '0012')
but the line which incudes this gets red and it says:
invalid syntax at '1'.Possibly, a),}, or] is missing
parse error at ')':usage might be invalid MATLAB syntax
so when i run it appears: un expected matlab expression... do you know what have i done wrong (again)? the values 1,10000 etc only in this line need to replace alfa,Re etc... am i wrong ?

No no, do NOT adjust the code itself! You should be calling the function from MATLAB, like any other function (fsolve(), ode45(), etc)

[nikolhs]

hi,
so i have the .m file unchanged (exactly the same with what you had attached in the first page) and i write in matlab command window :
[CL, CD] = get_coeffs(1.0, 40000, 0.2, '0012')but then appears the following message :
Undefined function or method 'get_coeffs' for input arguments of type 'double'.

please help... thnx

[azredwing]

hi,
so i have the .m file unchanged (exactly the same with what you had attached in the first page) and i write in matlab command window :
[CL, CD] = get_coeffs(1.0, 40000, 0.2, '0012')but then appears the following message :
Undefined function or method 'get_coeffs' for input arguments of type 'double'.

please help... thnx

Make sure you're currently in the same folder as get_coeffs() in MATLAB, or add the folder to your PATH.

[nikolhs]

i have put in the same folder the .m file and the pl file.i have xfoil in the same path which is referred in the .pl file.what else should i do ? it appears the same message:

>> [CL, CD] = get_coeffs(1.0, 40000, 0.3, '0012')
??? Undefined function or method 'get_coeffs' for input arguments of type 'double'.

[azredwing]

i have put in the same folder the .m file and the pl file.i have xfoil in the same path which is referred in the .pl file.what else should i do ? it appears the same message:

>> [CL, CD] = get_coeffs(1.0, 40000, 0.3, '0012')
??? Undefined function or method 'get_coeffs' for input arguments of type 'double'.

You're SURE that the MATLAB shell is in the same directory as get_coeffs.m ? Because that's what this error message is saying... if get_coeffs.m isn't in the current folder (default view is on the left side of the screen), it won't work. If it IS, then I'm kind of stuck...

[nikolhs]

what do you mean matlab shell ? how can i be sure for this ?