Control Function Generator with :APPL:SIN 200000

Hello, I´m currently working on a project to control an Rigol DG1022Z function generator. The following code works:

fprintf(Function_Generator, ':APPL:SIN 200000 ,%f ,0,0',V_start)

But I need to make the frequency varible like this:

f=200000;
fprintf(Function_Generator, ':APPL:SIN %f ,%f ,0,0',f,V_start)

to edit the frequency over a GUI. The code above sadly doesn´t work. Thanks for any help.

[Sebastian Frankl]

A friend helped me out. The answer is to seperate the string in different parts.

f=200000;
fprintf(Function_Generator, [':APPL:SIN ' num2str(f) ',%f ,0,0'],V_start);