@geeoddmike Thank you again sir for this explanation... it's very helpful

@john-hamilton thank you

Now space geodesy becomes a necessity...

@john-hamilton?ÿ Thank you very much, Please did you use the final extension (*.d) in your work? since they eliminated the extension (*.o).

@geeoddmike Thank you very much for your help. Please, In the routines?ÿI developed (Matlab code) to estimate the ionospheric TEC, I usually use the ...

@geeoddmike thank you for your response

@chris-bouffard Thank you for your response, I think it's hard to master Scilab?

@larry-scott?ÿThank you very much for your valuable help. Really much appreciated

@dallas-morlan?ÿThank you very much for your valuable help. Really much appreciated

@lee-d Thank you very much for your valuable help. Really much appreciated

@rover83 Thank you for your valuable help. Really much appreciated