![lapack]( "lapack")
本文介绍了从C ++链接到Fortran库（Lapack）的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
限时删除！！
我在C ++代码中使用。我很困惑如何正确链接到图书馆。这是一个与我的代码调用Lapack函数相对应的小例子：
#include< iostream>
namespace lapack {externC{
void ilaver（int * major，int * minor，int * patch）; }}
int main（）
{
int major = 0;
int minor = 0;
int patch = 0;
lapack :: ilaver（& major，& minor，& patch）;
std :: cout<<主要< <<次要<< <<补丁<<的std :: ENDL;
返回0;如果我尝试使用GCC 4.8.5（Linux openSUSE）进行编译，则可以使用以下命令来编译它：我收到以下错误消息： > g ++ ilaver.cpp -o ilaver -L /softs/lapack/3.7.1/64/gcc/4.8.5/lib64 -l lapack
/tmp/ccHvDCAh.o：在函数`main'中：
ilaver.cpp :(。text + 0x33）：对'ilaver'的未定义引用
collect2：错误：ld返回1退出状态
我知道这是一个名称混乱的问题。如果我在代码中添加一个下划线并在GCC中添加了下划线，那么它就可以正确编译GCC：
#include<的iostream>
namespace lapack {externC{
void ilaver_（int * major，int * minor，int * patch）; }}
int main（）
{
int major = 0;
int minor = 0;
int patch = 0;
lapack :: ilaver _（& major，& minor，& patch）;
std :: cout<<主要< <<次要<< <<补丁<<的std :: ENDL;
返回0;
}
但它不能在Windows下的英特尔编译器中编译。在那里，修改是不同的，我必须将它改为 lapack :: ILAVER ，然后编译它。
我的代码必须通过几种编译器（GCC，Intel，MSVC）在几种配置下编译（Linux / Mac / Windows）。我怎么能更通用，并确保它将在一大组编译器下编译？
解决方案
像添加下划线这样的黑客根据它们的性质是特定于平台的。支持大量平台和编译器的方式手工，需要大量的不愉快和繁琐的工作。
获得可移植性的最简单方法是使用LAPACKE，官方的C接口LAPACK。这还有一个好处，就是不必重新声明所有你需要的功能。
下面是一个简单的例子：
#include< iostream>
#include< lapacke.h>
int main（）
{
//通过使用lapack_int，我们也支持LAPACK-ILP64
lapack_int major = 0;
lapack_int minor = 0;
lapack_int patch = 0;
LAPACKE_ilaver（& major，& minor，& patch）;
std :: cout<<主要< <<次要<< <<补丁<<的std :: ENDL;
返回0;
}
更多信息可以在。
请注意，LAPACKE只处理LAPACK，如果你还需要BLAS例程，您可以从获取这些例程。
I'm using Lapack in my C++ code. I'm quite confused how to properly link to the library. Here is a small example corresponding to my code calling a function from Lapack:
#include <iostream>
namespace lapack { extern "C" {
void ilaver(int* major, int* minor, int* patch); } }
int main()
{
int major = 0;
int minor = 0;
int patch = 0;
lapack::ilaver(&major, &minor, &patch);
std::cout << major << "." << minor << "." << patch << std::endl;
return 0;
}
If I try to compile it with GCC 4.8.5 (Linux openSUSE), I get the following error:
> g++ ilaver.cpp -o ilaver -L /softs/lapack/3.7.1/64/gcc/4.8.5/lib64 -l lapack
/tmp/ccHvDCAh.o: In function `main':
ilaver.cpp:(.text+0x33): undefined reference to `ilaver'
collect2: error: ld returned 1 exit status
I understood it's a name mangling problem. If I change my code adding an underscore at the end of the function name, it compiles properly with GCC:
#include <iostream>
namespace lapack { extern "C" {
void ilaver_(int* major, int* minor, int* patch); } }
int main()
{
int major = 0;
int minor = 0;
int patch = 0;
lapack::ilaver_(&major, &minor, &patch);
std::cout << major << "." << minor << "." << patch << std::endl;
return 0;
}
But it doesn't compile with Intel's compilers under Windows. There, the mangling is different, I have to change it to lapack::ILAVER, and then it compiles.
My code must be compiled under several configurations (Linux/Mac/Windows) with several compilers (GCC,Intel,MSVC). How can I be more generic and be sure it will compile under a large panel of compilers ?
解决方案
As you have already discovered, hacks like adding the underscore are platform-specific by their nature. Supporting a big range of platforms and compilers that way "by hand" requires a large amount of unpleasant and tedious work.
The easiest way to get portability is to use LAPACKE, the official C interface to LAPACK. This also has the added benefit of saving you from having to re-declare all the functions you need.
Here's a simple example:
#include <iostream>
#include <lapacke.h>
int main()
{
// By using lapack_int, we also support LAPACK-ILP64
lapack_int major = 0;
lapack_int minor = 0;
lapack_int patch = 0;
LAPACKE_ilaver(&major, &minor, &patch);
std::cout << major << "." << minor << "." << patch << std::endl;
return 0;
}
More information can be found in the official documentation.
Note that LAPACKE only handles LAPACK, if you also need BLAS routines, you can get those from CBLAS.
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