Octave c++ and VS2010 - c++

I'm trying to Use Octave with Visual C++.
I have downloaded octave-3.6.1-vs2010-setup-1.exe. Created a new project, added octave include folder to include path, octinterp.lib and octave.lib to lib path, and I added Octave bin folder as running directory.
The program compiles and runs fine except feval function that causes the exception:
Microsoft C++ exception: octave_execution_exception at memory location 0x0012faef
and on Octave side:
Invalid resizing operation or ambiguous assignment to an out-of-bounds array element.
What am I doing wrong?
Code for a standalone program:
#include <octave/octave.h>
#include <octave/oct.h>
#include <octave/parse.h>
int main(int argc, char **argv)
{
if (octave_main (argc, argv, true))
{
ColumnVector NumRands(2);
NumRands(0) = 10;
NumRands(1) = 1;
octave_value_list f_arg, f_ret;
f_arg(0) = octave_value(NumRands);
f_ret = feval("rand",f_arg,1);
Matrix unis(f_ret(0).matrix_value());
}
else
{
error ("Octave interpreter initialization failed");
}
return 0;
}
Thanks in advance.

I tried it myself, and the problem seems to originate from the feval line.
Now I don't have an explanation as to why, but the problem was solved by simply switching to the "Release" configuration instead of the "Debug" configuration.
I am using the Octave3.6.1_vs2010 build, with VS2010 on WinXP.
Here is the code I tested:
#include <iostream>
#include <octave/oct.h>
#include <octave/octave.h>
#include <octave/parse.h>
int main(int argc, char **argv)
{
// Init Octave interpreter
if (!octave_main(argc, argv, true)) {
error("Octave interpreter initialization failed");
}
// x = rand(10,1)
ColumnVector sz(2);
sz(0) = 10; sz(1) = 1;
octave_value_list in = octave_value(sz);
octave_value_list out = feval("rand", in, 1);
// print random numbers
if (!error_state && out.length () > 0) {
Matrix x( out(0).matrix_value() );
std::cout << "x = \n" << x << std::endl;
}
return 0;
}
with an output:
x =
0.165897
0.0239711
0.957456
0.830028
0.859441
0.513797
0.870601
0.0643697
0.0605021
0.153486

I'd guess that its actually stopped pointing at the next line and the error actually lies at this line:
f_arg(0) = octave_value(NumRands);
You seem to be attempting to get a value (which value?) from a vector and then assigning it to element 0 of a vector that has not been defined as a vector.
I don't really know though ... I've never tried writing octave code like that. I'm just trying to work it out by translating the code to standard matlab/octave code and that line seems really odd to me ...

Related

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Inside listdlg.m, I can see this error is caused by if (__octave_link_enabled__ ()) on line 150. This is not set when octave is started with octave -cli. It is set however when octave --no-gui is used which I think is what I want the interpreter to use.
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I'm using the following C++ code to run my script:
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#include <octave/oct.h>
#include <octave/octave.h>
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main (int argc, char *argvc[])
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octave_main (2, argv.c_str_vec(), 1);
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{
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Segmentation fault occurs when PyRun_SimpleFile is called repeatedly

I want to embed a python code written in version 3.5 in c++. Also, the python script needs to be executed as the whole script repeatedly. My code as follows. It executes well for the first iteration and gives a segmentation fault at the second iteration.
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using namespace std;
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FILE* file;
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PyObject *sys = PyImport_ImportModule("sys");
PyObject *path = PyObject_GetAttrString(sys, "path");
PyList_Append(path, PyUnicode_FromString("."));
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PyRun_SimpleFile(file, "./example.py");
fclose(file);
Py_Finalize();
cout<<"Done"<<endl;
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example.py:
import tensorflow as tf
flags = tf.app.flags
FLAGS = flags.FLAGS
flags.DEFINE_float('learning_rate', 0.01, 'initial learning rate')
def main(argv=None):
print(FLAGS.learning_rate)
if __name__ == '__main__':
main()
I build the project using:
cmake --build . --target Demo -- -j 2
and executed as:
./Demo --learning_rate 0.02
The output was:
start
0.02
Done
start
Segmentation fault (core dumped)
Then I replaced the content of "example.py" as:
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The output was:
start
Hi
Done
start
Hi
Done
start
Hi
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How can I fix the above mentioned segmentation fault ?
See the docs
Some extensions may not work properly if their initialization routine is called more than once; this can happen if an application calls Py_Initialize() and Py_Finalize() more than once.

I invoke LSCopyApplicationURLsForURL() using C++, but get a segment fault

I want to write a C++ program to get associated applications which are suitable to open specified file. I find the LSCopyApplicationURLsForURL API, and create a command line C++ application by XCode.
But after running this program, I always get segment fault. XCode shows EXEC_BAD_ACCESS(code=1, address....) error.
I also tryied running it from sudo, but the same result. What is the problem?
The code:
#include <iostream>
#include <objc/objc.h>
#include <objc/objc-runtime.h>
#include <CoreFoundation/CoreFoundation.h>
#include <CoreServices/CoreServices.h>
using namespace std;
int main(int argc, const char * argv[]) {
auto url = CFURLRef("file:///Users/efan/src/a.cpp");
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cout << ret << endl;
return 0;
}
Try creating your CFURLRef using one of the proper CFURLCreate* methods. See "Creating a CFURL" here.
For example:
auto tempStringURL = CFStringCreateWithCString(nullptr, "/Users/efan/src/a.cpp", kCFStringEncodingUTF8);
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You need to Release the "Created" variables to clean up memory.

Using c++ libgpiod library, how can I set gpio lines to be outputs and manipulate single lines with set_value() function?

I just started using c++ bindings of libgpiod library and have problem with settings gpios. I know, that I can create long vector of values, and apply it in all at once, but I would like to be able to set their direction, and control them separately. How can I do that?
What I tried is this:
First: Working code with applying all values at once:
#include <gpiod.hpp>
int main(int argc, char **argv)
{
::gpiod::chip chip("gpiochip0");
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::gpiod::line_request requestOutputs = {
argv[0],
::gpiod::line_request::DIRECTION_OUTPUT,
0
};
int value_to_be_set = 0xAAAAAAA ; //example value
::std::vector<int> values;
for (int i = 0; i < 32; i++)
{
values.push_back((value_to_be_set >> i) & 1UL);
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lines.request(requestOutputs, values);
lines.release();
return EXIT_SUCCESS;
}
Second, my approach to do that I want:
#include <gpiod.hpp>
int main(int argc, char **argv)
{
::gpiod::chip chip("gpiochip0");
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::gpiod::line_request requestOutputs = {
argv[0],
::gpiod::line_request::DIRECTION_OUTPUT,
0
};
lines.request(requestOutputs);
int value_to_be_set = 0xAAAAAAA; //example value
for (int i = 0; i < 32; i++)
{
// This does not set value :(
lines.get(i).set_value((value_to_be_set >> i) & 1UL);
}
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return EXIT_SUCCESS;
}
I also could not find a simple C++ example to toggle a single GPIO line using the latest Raspberry PI libraries.
There is a multi-line example below but this is not what was originally asked:
https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/bindings/cxx
Below is an example that will cause GPIO17 to go high then low to create a single line output pulse.
// Use gpio drivers to toggle a single GPIO
// line on Raspberry Pi
// Use following commands to install prerequisites and build
// sudo apt install gpiod
// sudo apt install libgpiod-dev
// g++ -Wall -o gpio gpip.cpp -lgpiodcxx
#include <iostream>
#include <gpiod.hpp>
#include <unistd.h>
int main(void)
{
::gpiod::chip chip("gpiochip0");
auto line = chip.get_line(17); // GPIO17
line.request({"example", gpiod::line_request::DIRECTION_OUTPUT, 0},1);
sleep(0.1);
line.set_value(0);
line.release();
}
also don't forget to build with the flag -lgpiodcxx (for c++) or -lgpiod (for c)

How to use QueryPerformanceCounter to test performance of existing code?

I have an existing project in Visual Studio, with a main file that calls a function file. I also created a CodeTimer.cpp following the steps from the Microsoft guide, and I placed it along with the necessary headers in the same directory as my code and function.
The issue is, I don't know how to link them. The solution builds fine, all three files combine with no errors. But when I CTRL-F5 it, I just see the output of my main, for obvious reasons (I didn't link the CodeTimer to the main).
This is my CodeTimer:
#include "stdafx.h"
#include <tchar.h>
#include <windows.h>
using namespace System;
int _tmain(int argc, _TCHAR* argv[])
{
__int64 ctr1 = 0, ctr2 = 0, freq = 0;
int acc = 0, i = 0;
// Start timing the code.
if (QueryPerformanceCounter((LARGE_INTEGER *)&ctr1) != 0)
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// Code segment is being timed.
for (i = 0; i<100; i++) acc++;
// Finish timing the code.
QueryPerformanceCounter((LARGE_INTEGER *)&ctr2);
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Console::WriteLine("End Value: {0}", ctr2.ToString());
QueryPerformanceFrequency((LARGE_INTEGER *)&freq);
Console::WriteLine("QueryPerformanceFrequency : {0} per Seconds.", freq.ToString());
Console::WriteLine("QueryPerformanceCounter minimum resolution: 1/{0} Seconds.", freq.ToString());
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Console::WriteLine("65536 Increments by 1 computation time: {0} seconds.", ((ctr2 - ctr1) * 1.0 / freq).ToString());
}
else
{
DWORD dwError = GetLastError();
Console::WriteLine("Error value = {0}", dwError.ToString());
}
// Make the console window wait.
Console::WriteLine();
Console::Write("Press ENTER to finish.");
Console::Read();
return 0;
}
NVM fixed it. Just had to add the body of _tmain() in main() function under my code, and get ride of the CodeTimer.cpp file completely. It was a conflict of mains (multiple mains in one project, the compiler automatically outputted the one with the highest priority in the project).