MPI上的矩阵向量乘法-错误编译代码

Question

我需要帮助来解决以下代码中的错误：

#include <iostream>
#include <mpi.h>
using namespace std;
//matrix in two dimension in memory!!
int main(int argc, char** argv)
{
const int WIDTH = 100;
const int HEIGHT = 100;
int id, P;
double tempValue = 0;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &P);
MPI_Comm_rank(MPI_COMM_WORLD, &id);
double A[WIDTH][HEIGHT];
double x[HEIGHT], b[WIDTH];
int upperBound, lowerBound = 0;
// Master controls worksharing..
if (id == 0)
{
// Init A & x
for (int i = 0; i < WIDTH; i++)
for (int j = 0; j < HEIGHT; j++)
A[i][j] = 1;
for (int j = 0; j < HEIGHT; j++)
x[j] = 2;
// Send to each node its portion of A to be processed
int portionSize = WIDTH / P;
for (int i = 0; i < P; i++)
{
lowerBound = i * portionSize;
upperBound = (i + 1) * portionSize;
// let the last node process the remainder
if (i == (P - 1))
upperBound += (HEIGHT - portionSize * P);
if (i > 0)// Do not send to master node!!
{
// Send to node i the lower & upper bounds the A portion
//and complete vector x
MPI_Send(&lowerBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD);
MPI_Send(&upperBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD);
MPI_Send(&A[lowerBound][0], (upperBound - lowerBound) * HEIGHT,
MPI_DOUBLE, i, 0, MPI_COMM_WORLD);
MPI_Send(&x[0], HEIGHT, MPI_DOUBLE, i, 0, MPI_COMM_WORLD);
}
}
// master perform part of the job...
for (int i = 0; i < portionSize; i++)
{
tempValue = 0;
for (int j = 0; j < HEIGHT; j++)
tempValue += A[i][j] * x[j];
b[i] = tempValue;
}
//Get the results in order, each node would send their boundaries and data part
for (int i = 1; i < P; i++)
{
MPI_Recv(&lowerBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&upperBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&P[lowerBound], (upperBound - lowerBound), MPI_DOUBLE, i, 0,
MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
}
// Print the first 2 values to check..
cout << "b[0]=" << b[0] << " b[Width-1]=" << b[WIDTH - 1] << endl;
}
else // the rest of the workers do their parts
{
//Receive the inputs
MPI_Recv(&lowerBound, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&upperBound, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&A[lowerBound][0], (upperBound - lowerBound) * WIDTH, MPI_DOUBLE, 0, 0,
MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&x, HEIGHT, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
cout << "Node:" << id << " Received from:" << lowerBound << " to " << upperBound - 1
<< endl;
double* result = new double[upperBound - lowerBound];
//Do the job
for (int i = lowerBound, resultCounter = 0; i < upperBound; i++, resultCounter++)
{
tempValue = 0;
for (int j = 0; j < HEIGHT; j++)
tempValue += A[i][j] * x[j];
result[resultCounter] = tempValue;
}
//send the results
MPI_Send(&lowerBound, 1, MPI_INT, 0, 0, MPI_COMM_WORLD);
MPI_Send(&upperBound, 1, MPI_INT, 0, 0, MPI_COMM_WORLD);
MPI_Send(&result[0], upperBound - lowerBound, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD);
delete[] result;
}
MPI_Finalize();
return 0;
}

当我在Microsoft Visual Studio 2019中编译代码时，我收到以下错误消息：

错误(活动(E0142表达式必须具有指向对象类型ConsoleApplication9 C:\Users\m_swe\Desktop\Assignments\Assignations\PrjP2\MatMPI\MatMPI\Source.cpp 59的指针
错误C2109下标需要数组或指针类型ConsoleAApplication9 C:\Useres\m_swe\Disktop\Aassignments\PrjP2P \MatMPI\MatMPI\Source.chpp 59

Answer 1

我认为问题出在行：59

MPI_Recv(&P[lowerBound], (upperBound - lowerBound), MPI_DOUBLE, i, 0,

MPI_Recv接收一个指向缓冲区(第一个参数(的指针，您将在该缓冲区接收和存储传入数据。在这种情况下，它可能在一些变量中，您可以在for循环中定义为：

int receivedValues[ WIDTH * HEIGHT ];
for (int i = 1; i < P; i++)
{
MPI_Recv(&lowerBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&upperBound, 1, MPI_INT, i, 0, MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
MPI_Recv(&receivedValues[0], (upperBound - lowerBound), MPI_DOUBLE, i, 0,
MPI_COMM_WORLD, MPI_STATUSES_IGNORE);
// do your computation here with receivedValues
}
}