Seeing gnuplot error messages in output

[MikeGitb]

Bug category

• bug - compilation error
• bug - compilation warning
• bug - runtime error
• bug - runtime warning
• bug - logic error

Describe the bug

I have a similar problem as #27. In my case it seems that another command is split (see repro). However the plot is displayed correctly (best I can tell)
I should mention that I'm using th version from vcpkg, which seems to be about a year old (package version is given as 2021-04-11#5).

Steps to Reproduce
Compiling the following program

Compiling the following program
#include <matplot/matplot.h>
#include <iostream>

int main() {
    std::vector<double> a{1,2,3,4,5}, b{-1,-0.7,0,0.7,1};
    matplot::figure();
    std::cout << "============  " << 1 << " ================  " << std::endl;
    matplot::plot(a, b);
    std::cout << "============  " << 2 << " ================  " << std::endl;
    matplot::show();
}

In visual studio 2022 (cmake project via "open folder" and using vcpkg in maifest mode to get matplotlplusplus)

Output

============  1 ================

gnuplot> se
           ^
         line 0: unrecognized option - see 'help set'.


gnuplot> t terminal wxt title "Figure 1" size 560,420 enhanced font "Sans,10"
         ^
         line 0: invalid command

============  2 ================

gnuplot> se
           ^
         line 0: unrecognized option - see 'help set'.


gnuplot> t terminal wxt title "Figure 1" size 560,420 enhanced font "Sans,10"
         ^
         line 0: invalid command


gnuplot> se
           ^
         line 6: unrecognized option - see 'help set'.


gnuplot> t terminal wxt title "Figure 1" size 560,420 enhanced font "Sans,10"
         ^
         line 6: invalid command

Press ENTER to continue...

Platform

• cross-platform issue - linux
• cross-platform issue - windows
• cross-platform issue - macos

Environment Details:

• OS: Windows 10
• OS Version: 21H1
• Compiler: msvc
• Compiler version: From the cmake log: "The CXX compiler identification is MSVC 19.31.31104.0"

Additional context

When I start gnuplot manually, I get the following output:

        G N U P L O T
        Version 5.4 patchlevel 3    last modified 2021-12-24

        Copyright (C) 1986-1993, 1998, 2004, 2007-2021
        Thomas Williams, Colin Kelley and many others

        gnuplot home:     http://www.gnuplot.info
        faq, bugs, etc:   type "help FAQ"
        immediate help:   type "help"  (plot window: hit 'h')

Terminal type is now 'wxt'
Options are '0 enhanced'
Encoding set to 'cp1252'.
gnuplot>

[nigeljw3]

I am also seeing this identical problem with a custom debug build from trunk and also a package release build from vcpkg.

[nigeljw3]

So I reinstalled gnuplot and then set the GNUTERM to use "windows" and I no longer have this issue.

I tried to explicitly set QT previously, but had the same issue as whatever was default on the first install.

[nigeljw3]

Looks like I get a similar issue if I try to save an image instead of just showing the plot.

gnuplot> t output "plot.png"
^
line 22: invalid command

‰PNG
→
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[alandefreitas]

That's intended behavior because they're errors. At most, we could have a flag in the backend to turn that off.

[MikeGitb]

@alandefreitas : What is intended behavior?

[KelbyVP]

That's intended behavior because they're errors. At most, we could have a flag in the backend to turn that off.

Alan, I'm getting this error when I copy your code from your "Saving Programatically" page. It keeps me from saving the image. So, the sample code shown on your page doesn't work. If there are errors here, how do we go about saving in a way that doesn't produce these errors?