Alglib with Cuda

Question

I am pretty new with alglib and Cuda. I am trying to use Alglib for nonlinear list square fitting. Codes are working when I compile it in VC++ (.cpp) but when I am trying to compile same code but in a cuda file (.cu) it gives me this error:

Error   6   error C2668: 'round' : ambiguous call to overloaded function    
Error   7   error C2668: 'round' : ambiguous call to overloaded function    
Error   8   error C2668: 'round' : ambiguous call to overloaded function    
Error   9   error C2668: 'trunc' : ambiguous call to overloaded function    

Error   10  error MSB3721:

The command ""D:\NVIDIA\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" --use-local-env --cl-version 2012 -ccbin "D:\Programme (x86)\Microsoft Visual Studio 11.0\VC\bin" -ID:\NVIDIA\include -ID:\NVIDIA\include --keep-dir Release -maxrregcount=0 --machine 32 --compile -cudart static -D_MBCS -Xcompiler "/EHsc /W3 /nologo /O2 /Zi /MD " -o Release\min.cu.obj "...\min.cu"" exited with code 2. C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V110\BuildCustomizations\CUDA 6.0.targets 597 9 Cuda_lsfit

Here is my codes :

# include <iostream>
# include "cuda_runtime.h"
# include "device_launch_parameters.h"
# include <cuda.h>
#include "stdafx.h"
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "interpolation.h"

using namespace alglib;

void function_cx_1_func(const real_1d_array &c, const real_1d_array &x, double &func,      void *ptr) 
{
  // main function
   func = abs(c[0]*(1-exp(-x[0]/c[1])));;
}

int main(int argc, char **argv)
{
real_2d_array x = "[[50],[400],[550],[750],[1200],[2000]]";
real_1d_array y = "[1384,792,642,258,91,868]";
real_1d_array c = "[0.5,500]";
double epsf = 0; //minimum of step size difference
double epsx = 0.000001;  //minimum of function changes
ae_int_t maxits = 0; //maximum iteration 0 = unlimitted number
ae_int_t info;
lsfitstate state; // structure contains information about algoritm
lsfitreport rep;
double diffstep = 0.0001;

// Fitting 

lsfitcreatef(x, y, c, diffstep, state);
lsfitsetcond(state, epsf, epsx, maxits);
alglib::lsfitfit(state, function_cx_1_func);
lsfitresults(state, info, c, rep);
printf("%d\n", int(info)); 
printf("%s\n", c.tostring(1).c_str()); 

return 0;
}

Any solution would be appreciated.

Thanks, Mohsen

If you want to ask a "why doesn't this code compile" question, you will need to post the shortest code which demonstrates the problem. — talonmies
I solve it but honestly I am not sure if it is the best solution. I just defined the round function and trunc should use from alglib library. now it compiles and it gives me correct result. — mohsen67
I do not see any calls to trunc() or round() in the posted code. These functions are supported in CUDA device code and they are overloaded for argument types of float and double. Calling with an argument of any other type could cause the kind of error message you are seeing. However the error messages you are showing seem to be MSVC error messages, so the problem seems to be in the host code portion of the .cu file. Check the prototypes in the host header files (are you including all necessary header files ?) and compare the argument type passed inside the application code. — njuffa
@njuffa: I wonder whether this is a namespace conflict resulting from the using namespace alglib; — talonmies
@talonmies: I do not have any experience with, or insight into, the use of namespaces in .cu file. When there are issues with the host code (as appears to be the case here), my standard recommendation is to move the affected code out of the .cu and into a .cpp file. — njuffa

Unknown Unknown · Accepted Answer · 2016-02-22T06:35:10

This would appear to have been a namespace conflict between the definitions of mathematical functions which CUDA adds during compilation, and including the whole alglib namespace into the translation unit. Removing

using namespace alglib;

from the code apparently solved the problem.

In general, unconditionally importing a large namespace into another is a very poor design practice in C++, because it can lead to very hard to diagnose conflicts like this, as well as slowing down compilation.

Alglib with Cuda

1 Answers