Question about Octave 4.0.3 and 4.2.1

[Zhihui Zou]

Hi guys,

I am trying to call Octave functions from C++. For Octave 4.0.3, everything is 
going great. But when I call the plot function, there is no response at all. My 
system is MacOS, and I tried many ways online, but none of them worked out. I 
definitely installed gnuplot, because I can use the plot function with Octave 
4.2.1 in terminal. But the clean_up_and_exit() function seems not work for 
Octave 4.2.1 when calling Octave from C++. 

Anybody can help me out?  Either helping me figure out the no-response problem 
with plot function in Octave 4.0.3, or how to fixing the clean_up_and_exit() 
problem in Octave 4.2.1 would be OK. So I can call Octave functions from C++. 
Thank you very much.

Really appreciate.