jacobi.cpp

热分布问题实现

/* 热分布问题*/

#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
#include <gl/glut.h>
#include <gl/gl.h>
#include <gl/glu.h>

#define LIMIT 1000
#define bottom_value 1.0
#define top_value 1.0
#define left_value 1.0
#define right_value 1.0
#define ROW 200
#define COL 200



float h[ROW][COL],g[ROW][COL];

void SetupRC (void) ;	//初始化OpenGL场景

void RenderScene(void) ;	//场景的绘制函数

void ChangeSize(GLsizei width, GLsizei height) ;

void Calculate(int highrow, int lowrow, int myid, int numprocs)
{
	int j , k , iteration ;

	for(iteration=0;iteration<LIMIT;iteration++)
	{
		for(k=lowrow;k<=highrow;k++)
		{
			for(j=0;j<COL;j++)
			{
				if(k==0)
					g[k][j]=bottom_value;
				else if(k==ROW-1)
					g[k][j]=top_value;
				else if(j==0||j==COL-1)
					g[k][j]=h[k][j];
				else
					g[k][j]=0.25*(h[k-1][j]+h[k+1][j]+h[k][j-1]+h[k][j+1]);
			}
		}
			
		for(k=lowrow;k<=highrow;k++)
			for(j=0;j<COL;j++)
				h[k][j]=g[k][j];

		if(numprocs>1)
		{
			if(myid%2==0)//若是偶数号进程则先发送后接收
			{
				if(myid>0)
					MPI_Send(&g[lowrow][0],COL,MPI_FLOAT,myid-1,0,MPI_COMM_WORLD);
				if(myid<numprocs-1)
					MPI_Send(&g[highrow][0],COL,MPI_FLOAT,myid+1,0,MPI_COMM_WORLD);

				if(myid<numprocs-1)
					MPI_Recv(&h[highrow+1][0],COL,MPI_FLOAT,myid+1,0,MPI_COMM_WORLD,0);
				if(myid>0)
					MPI_Recv(&h[lowrow-1][0],COL,MPI_FLOAT,myid-1,0,MPI_COMM_WORLD,0);				
			}
			else//若是奇数号进程则先接收后发送
			{
				if(myid<numprocs-1)
					MPI_Recv(&h[highrow+1][0],COL,MPI_FLOAT,myid+1,0,MPI_COMM_WORLD,0);
				if(myid>0)
					MPI_Recv(&h[lowrow-1][0],COL,MPI_FLOAT,myid-1,0,MPI_COMM_WORLD,0);
				
				if(myid>0)
					MPI_Send(&g[lowrow][0],COL,MPI_FLOAT,myid-1,0,MPI_COMM_WORLD);
				if(myid<numprocs-1)
					MPI_Send(&g[highrow][0],COL,MPI_FLOAT,myid+1,0,MPI_COMM_WORLD);
			}
		}
	}
}

int main(int argc,char *argv[])
{
	int myid,numprocs;
	
	int step,highrow,lowrow ;
	int i,j,k;

	MPI_Init(&argc,&argv);
	MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
	MPI_Comm_rank(MPI_COMM_WORLD,&myid);

	//数据赋初值
	step=ROW/numprocs;
	lowrow=myid*step;
	if(myid==numprocs-1)
		highrow=ROW-1;
	else
		highrow=lowrow+step-1;

	if(myid==0)
	{
		printf("Processes number: %d\n",numprocs);

		//初始化数据：
		for(i=0;i<ROW;i++)
		{
			for(j=0;j<COL;j++)
			{
				if(i==0)
				{
					h[i][j]=bottom_value;
					continue;
				}
				if(i==ROW-1)
				{
					h[i][j]=top_value;
					continue;
				}
				if(j==0)
				{
					h[i][j]=left_value;
					continue;
				}
				if(j==COL-1)
				{
					h[i][j]=right_value;
					continue;
				}
				h[i][j]=0.0;
			}
		}

		//分配任务,将初始数据送到各个进程
		for(i=1;i<numprocs;i++)
		{
			j=i*step;
			if(i!=numprocs-1)
			{
				MPI_Send(&h[j][0],step*COL,MPI_FLOAT,i,0,MPI_COMM_WORLD);
			}
			else
			{
				k=ROW-i*step;
				MPI_Send(&h[j][0],k*COL,MPI_FLOAT,i,0,MPI_COMM_WORLD);
			}
		}

		Calculate( highrow,  lowrow, myid, numprocs) ;
			
		//接收各个进程送来的数据
		for(i=1;i<numprocs;i++)
		{
			j=i*step;
			if(i!=numprocs-1)
				MPI_Recv(&h[j][0],COL*step,MPI_FLOAT,i,0,MPI_COMM_WORLD,0);
			else
			{
				k=ROW-i*step;
				MPI_Recv(&h[j][0],COL*k,MPI_FLOAT,i,0,MPI_COMM_WORLD,0);
			}
			printf("Received data from process %d\n",i);
		}
		MPI_Finalize();			//0号进程MPI_Finalize()的正确位置
				
		//绘制计算结果：
		glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
		glutInitWindowSize(COL , ROW);
		glutCreateWindow("Jacobi");
		glutDisplayFunc(RenderScene);
		glutReshapeFunc(ChangeSize);
		
		SetupRC();
		glutMainLoop();			
	}

	else
	{
		if(myid!=numprocs-1)
			MPI_Recv(&h[lowrow][0],COL*step,MPI_FLOAT,0,0,MPI_COMM_WORLD,0);
		else
		{
			k=ROW-myid*step;
			MPI_Recv(&h[lowrow][0],COL*k,MPI_FLOAT,0,0,MPI_COMM_WORLD,0);
		}

		Calculate( highrow,  lowrow, myid, numprocs) ;
			 
		//向主进程发送数据
		if(myid!=numprocs-1)
			MPI_Send(&h[lowrow][0],COL*step,MPI_FLOAT,0,0,MPI_COMM_WORLD);
		else
		{
			k=ROW-myid*step;
			MPI_Send(&h[lowrow][0],COL*k,MPI_FLOAT,0,0,MPI_COMM_WORLD);
		}
		
		MPI_Finalize();			//其他进程MPI_Finalize()的正确位置
	}
	
	//MPI_Finalize();		
	/*  MPI_Finalize()不可以放在这里，因为0号进程已经把控制权移交给glutMainLoop()，
		所以0号进程的glutMainLoop()之后的代码不会被执行，
		其他进程的MPI_Finalize()因此也不会执行完毕，进程不会自动结束 */
	
	printf("Process %d exited.\n",myid);
	return 0;
}



//初始化OpenGL场景
void SetupRC (void)
{
	glClearColor (0.0, 0.0, 0.0, 0.0);		
	glShadeModel (GL_FLAT);	//设置明暗处理 
}

void RenderScene(void)
{
	int i,j;	
	glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	//清除缓存
	
	glBegin(GL_POINTS);				//开始画点
	for(i=0; i<ROW; i++)
		for(j=0; j<COL; j++)
		{
			glColor3f (h[i][j], 0.0f, 0.0f);	//设置颜色为红色 
			glVertex3f((float)j,float(i),0.0);	//设置点在世界坐标系中的坐标
		}

	glEnd();		//画点结束	
	glutSwapBuffers();

}


// Called by GLUT library when the window has chanaged size
void ChangeSize(GLsizei width, GLsizei height)
{
	// Prevent a divide by zero
	if(height == 0)
		height = 1;
	// Set Viewport to window dimensions
	glViewport((width-COL)/2, (height-ROW)/2, COL, ROW);
	// Reset coordinate system
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	// Establish clipping volume (left, right, bottom, top, near, far)  
	glOrtho (0, COL, 0, ROW, -1, 1);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
}