LNK1169: one or more multiply defined symbols found.
My project is a parallelized random number generator, using MPI and the parallel prefix algorithm. I have looked up many solutions to LNK1169 errors. To try to prevent it I made many variables static, I looked for multiply defined variables, and cannot find any. I have no header files where variables could have been multiply defined. If anyone could help me find the error I would greatly appreciate it. I am fairly sure the error occurs in functions.cpp somewhere, as everything was building correctly before I attempted to implement the parallel_prefix function.
Also here is the output from LNK2005:
LNK2005 "class std::vector >,class std::allocator > > > __cdecl parallel_prefix(class std::vector >,class std::allocator > > >,class std::allocator >,class std::allocator > > > > >,int,int)" (?parallel_prefix@@YA?AV?$vector@V?$vector@HV?$allocator@H@std@@@std@@V?$allocator@V?$vector@HV?$allocator@H@std@@@std@@@2@@std@@V?$vector@V?$vector@V?$vector@HV?$allocator@H@std@@@std@@V?$allocator@V?$vector@HV?$allocator@H@std@@@std@@@2@@std@@V?$allocator@V?$vector@V?$vector@HV?$allocator@H@std@@@std@@V?$allocator@V?$vector@HV?$allocator@H@std@@@std@@@2@@std@@@2@@2@HH@Z) already defined in functions.obj RandomNumberGenerator
Here is my code.
RandomNumberGenerator.cpp
#include "functions.cpp"
int main(int argc, char *argv[])
{
// Establishes what rank it is, and how many processes are running.
static int rank, p, n, per_Process;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &p);
static vector<int> Broadcast_data;
n = 100;
per_Process = n / p;
// The first and second arguments are constants for number generation, the third is a large prime to mod by, and the fourth is a random seed. x1 is calculated based off x0.
// All provided by the user except x1.
// Rank 0 broadcasts the data to all processes.
if (rank == 0)
{
for (static int i = 1; i < 5; i++)
{
Broadcast_data.push_back(std::atoi(argv[i]));
}
Broadcast_data.push_back(std::atoi(argv[1]) *std::atoi(argv[4]) % std::atoi(argv[3]));
// NOTE: THIS PUSH BACK IS HOW MANY RANDOM NUMBERS WILL BE GENERATED
Broadcast_data.push_back(n);
cout << "Rank " << rank << " Broadcast Data: ";
for (static int i = 0; i < 6; i++)
{
cout << Broadcast_data[i] << " ";
}
cout << endl;
}
else
{
Broadcast_data.resize(6);
}
MPI_Bcast(Broadcast_data.data(), 6, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Barrier(MPI_COMM_WORLD);
// Initialize an array of n/p values at every process. Each of the n/p values is the matrix M.
// M is this 2 dimmensional array:
// [ a 1 ]
// [ b 0 ]
static vector<vector<int>> M;
M.resize(2);
M[0].resize(2);
M[1].resize(2);
M[0][0] = Broadcast_data[0];
M[0][1] = Broadcast_data[1];
M[1][0] = 1;
M[1][1] = 0;
// Now we must initialize the array of these M values. Notation might get complex here
// as we are dealing with 3D arrays.
static vector<vector<vector<int>>> M_values;
M_values.resize(per_Process);
for (static int i = 0; i < per_Process; i++)
{
M_values.push_back(M);
}
// Now we are ready for the parallel prefix operation. Note that the operator here
// is matrix multiplication.
static vector<vector<int>> prefix;
prefix = parallel_prefix(M_values, rank, p);
MPI_Finalize();
return 0;
}
functions.cpp
#include <mpi.h>
#include <iostream>
#include <cstdlib>
#include <string>
#include <vector>
#include <time.h>
using namespace std;
// This is parallel prefix with the operator being matrix multiplication
vector<vector<int>> parallel_prefix(vector<vector<vector<int>>> Matrices, int rank, int p)
{
// The first step is a local multiplication of all M values.
// In a matrix represented by:
// [ a b ]
// [ c d ]
// The new matrix will be this:
// [ a^2+bc ab+bd ]
// [ ca+dc cb+d^2 ]
// So the first step will be to complete this operation once for every matrix M in M_values
static vector<vector<int>> local_sum;
local_sum = Matrices[0];
for (static int i = 1; i < Matrices.size(); i++)
{
vector<vector<int>> temp_vector;
temp_vector = local_sum;
temp_vector[0][0] = local_sum[0][0] * Matrices[i][0][0] + local_sum[1][0] * Matrices[i][0][1];
temp_vector[0][1] = local_sum[0][1] * Matrices[i][0][0] + local_sum[1][1] * Matrices[i][0][1];
temp_vector[1][0] = local_sum[0][0] * Matrices[i][1][0] + local_sum[0][1] * Matrices[i][1][1];
temp_vector[1][1] = local_sum[0][1] * Matrices[i][1][0] + local_sum[1][1] * Matrices[i][1][1];
local_sum = temp_vector;
}
// Now that all the local sums have been computed we can start step 2: communication.
// Determine how many steps it will take
int steps = 0;
while (int j = 1 < p)
{
j *= 2;
steps++;
}
while (int k = 0 < steps)
{
// First determine the rank's mate.
static int mate;
mate = rank | (1u << steps);
// Now we send the local sum to mate, and receive our mate's local sum.
// First modify the local sum vector to a vector that can be sent.
// Send vector syntax is [ a c b d ]
static vector<int> send_vector, recv_vector;
send_vector.resize(4);
recv_vector.resize(4);
send_vector[0] = local_sum[0][0];
send_vector[1] = local_sum[0][1];
send_vector[2] = local_sum[1][0];
send_vector[3] = local_sum[1][1];
// Send the vector to your mate, and recieve a vector from your mate.
static MPI_Status status;
MPI_Send(send_vector.data(), 4, MPI_INT, mate, 0, MPI_COMM_WORLD);
MPI_Recv(recv_vector.data(), 4, MPI_INT, mate, 1, MPI_COMM_WORLD, &status);
// Update the local sum if your mate rank is lower than your rank.
if (mate < rank)
{
static vector<vector<int>> temp_vector;
temp_vector = local_sum;
temp_vector[0][0] = local_sum[0][0] * recv_vector[0] + local_sum[1][0] * recv_vector[1];
temp_vector[0][1] = local_sum[0][1] * recv_vector[0] + local_sum[1][1] * recv_vector[1];
temp_vector[1][0] = local_sum[0][0] * recv_vector[2] + local_sum[0][1] * recv_vector[3];
temp_vector[1][1] = local_sum[0][1] * recv_vector[2] + local_sum[1][1] * recv_vector[3];
local_sum = temp_vector;
}
MPI_Barrier(MPI_COMM_WORLD);
k++;
// After completion of this loop the local sum is the parallel prefix output for each process.
}
return local_sum;
}
You're including functions.cpp in main.cpp, and probably also including it in your project. This compiles the things in functions.cpp twice.
Don't include functions.cpp in main. Use functions.h to declare the functions from within it.