programming data to be saved into a 2D wave

Menu "Macros"
    "Make Wave and Graph", menuMakeWaveAndGraph()
end

Function menuMakeWaveAndGraph()

    Variable amp=1, tau=3, x1=0, x2=30
    Prompt amp, "Amplitude:"
    Prompt tau, "Decay Constant:"
    Prompt x1, "Starting X value:"
    Prompt x2, "Ending X value:"
   
    DoPrompt "Make a Wave and Graph", amp, tau, x1, x2
    if (V_flag == 0)
        MakeWaveAndGraph(amp, tau, x1, x2)
    endif
end

Function MakeWaveAndGraph(amp, tau, x1, x2)
    Variable amp, tau, x1, x2
   
    Make/N=200/O graphwave
    SetScale/I x x1, x2, graphwave
    graphwave = amp*exp(-x/tau)
    Display graphwave
end