openCL实现计算自然对数

主要是之前老师让不同的方法实现计算自然对数，了解不同并行语言的特点。所以在用了多线程，openMP后，想用opencL实现以下，先介绍一下算法

 

 

方法一.

 代码主机端

/*
   项目：openCL的矩阵相乘
   作者：刘荣
   时间：2012.11.20
*/
#include 
#include
#include  
#include
#include 
#include 
#include 
using namespace std;
//kernel函数
std::string
convertToString(const char *filename)//将kernel源码，即自己写的并行化的函数，转化成字符串
{
    size_t size;
    char*  str;
    std::string s;

    std::fstream f(filename, (std::fstream::in | std::fstream::binary));

    if(f.is_open())
    {
        size_t fileSize;
        f.seekg(0, std::fstream::end);
        size = fileSize = (size_t)f.tellg();
        f.seekg(0, std::fstream::beg);

        str = new char[size+1];
        if(!str)
        {
            f.close();
            std::cout << "Memory allocation failed";
            return NULL;
        }

        f.read(str, fileSize);
        f.close();
        str[size] = '\0';
    
        s = str;
        delete[] str;
        return s;
    }
    else
    {
        std::cout << "\nFile containg the kernel code(\".cl\") not found. Please copy the required file in the folder containg the executable.\n";
        exit(1);
    }
    return NULL;
}

int main()
{
	//
	double start,end,time1,time2;
	//查询平台
	cl_int ciErrNum;
	cl_platform_id platform;
	ciErrNum = clGetPlatformIDs(1, &platform, NULL);
	if(ciErrNum != CL_SUCCESS)
	{
		cout<<"获取设备失败"<

kernel函数

// Enter your kernel in this window
__kernel
void CaluE(__global double* result,
           int StepNum,
           int MaxItem
 )
{
    int id=get_global_id(0);
    double start,end,res;
	int offest = StepNum/MaxItem;
	//获得所求的初末
	start = id+1;
	end = id+offest;
	//开始计算
	res = 0;
	double fact = 1;

	for(int i = start; i < end; i++)
	{
		fact *= i;
		res += (1.0/fact);
	}
	//传回   
    result[id*2] = res; 
	result[id*2+1] = fact;
        
	barrier(CLK_LOCAL_MEM_FENCE);  
};

 

方法二

主机端程序

/*
   项目：openCL的矩阵相乘
   作者：刘荣
   时间：2012.11.20
*/
#include 
#include
#include  
#include
#include 
#include 
#include 
using namespace std;
//kernel函数
std::string
convertToString(const char *filename)//将kernel源码，即自己写的并行化的函数，转化成字符串
{
    size_t size;
    char*  str;
    std::string s;

    std::fstream f(filename, (std::fstream::in | std::fstream::binary));

    if(f.is_open())
    {
        size_t fileSize;
        f.seekg(0, std::fstream::end);
        size = fileSize = (size_t)f.tellg();
        f.seekg(0, std::fstream::beg);

        str = new char[size+1];
        if(!str)
        {
            f.close();
            std::cout << "Memory allocation failed";
            return NULL;
        }

        f.read(str, fileSize);
        f.close();
        str[size] = '\0';
    
        s = str;
        delete[] str;
        return s;
    }
    else
    {
        std::cout << "\nFile containg the kernel code(\".cl\") not found. Please copy the required file in the folder containg the executable.\n";
        exit(1);
    }
    return NULL;
}

int main()
{
	//
	double start,end,time1,time2;
	//查询平台
	cl_int ciErrNum;
	cl_platform_id platform;
	ciErrNum = clGetPlatformIDs(1, &platform, NULL);
	if(ciErrNum != CL_SUCCESS)
	{
		cout<<"获取设备失败"<

 

kernel函数

// Enter your kernel in this window
__kernel
void CaluE(__global double* result,
           int StepNum,
           int MaxItem
 )
{
    int id = get_global_id(0);
    float fact = 1;
	double e = 0;
	for(int i = id+1; i <= StepNum;i+=MaxItem)
	{
		for(int j=0; j

 

// Enter your kernel in this window
__kernel
void CaluE(__global double* result,
           int StepNum,
           int MaxItem
 )
{
    int id=get_global_id(0);
    double start,end,res;
	int offest = StepNum/MaxItem;
	//获得所求的初末
	start = id+1;
	end = id+offest;
	//开始计算
	res = 0;
	double fact = 1;

	for(int i = start; i < end; i++)
	{
		fact *= i;
		res += (1.0/fact);
	}
	//传回   
    result[id*2] = res; 
	result[id*2+1] = fact;
        
	barrier(CLK_LOCAL_MEM_FENCE);  
};