How to resolve an error message: Unrecognized function or variable

I always get an error of Unrecognized function 'DA' when I run the code for the first time.

The error disappears in subsequent runs. What could be the reason.

see a sample of the code.

%%  ENTER DATE, MONTH, YEAR AND HOUR

    DA.Day = 1;
    DA.Month = 06; 
    DA.Year = 2021;

    DA.tLST = 7;        
    DA.ls   = 60;     
    
     [tim, yprime] = Balloondynamics(dtspan,In0,wind, DA, I, B);
     
 

[Image Analyst]

This code will run fine the first time. You must be running a version where somehow DA never got assigned, but we can't tell because, unfortunately, you forgot to attach ESC_simulation.m.

[Sulaymon Eshkabilov]

It seems that you may have an M-file called DA in your current or working (accessible) directory/ies. Check it.

[Walter Roberson]

@Sulaymon Eshkabilov

No, if there was a DA.m in the path and no variable with that name, then it would not have been an unrecognized function: it would in that case have attempted to execute DA with no arguments, and it would have errored if DA did not return any values.

[Telema Harry]

Thank you for the feedback @Image Analyst @Walter Roberson @Sulaymon Eshkabilov.

I have seen the bug. It took a while but I was able to find it.

after the DA variable, I called another file to load weather data.

That file clears all the previous variables using the function: clearvars -except data

In the next attempt, the program uses the stored 'data' and it is not runing the weather data file again.

Problem solved. Thanks

[Rik]

That sounds like you just learned why functions are useful.