C++ :: Matrix Vector Multiplication
Jan 30, 2015
I have Problem with matrix vector multiplication in program..
void matrixVector ( const int n, const double* A, const double* x, double* y ){
//for(int i = 0; i < n; i++){
// y[i*n] = 0.0;
// }
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
y[i*n] += A[i*n+j]*x[j*n];
[Code] ....
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Jun 1, 2014
I just want to know the code of the program: Write code to accept matrix as aurgument and display its multiplication matrix which return its multiplication matrix.
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Feb 15, 2014
Code:
#include<stdio.h>
#include<conio.h>
void main()
[Code] .....
This program on running returns an error of "ILLEGAL USE OF POINTER".
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Feb 17, 2014
Code:
#include<stdio.h> Code: #include<conio.h>
void main() {
int *a[2][2],*b[2][2],*c[2][2],i,j,k;
Printf("
ENTER a MATRIX ELEMENTS
[Code] .....
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Apr 25, 2014
I have been using SSE/ SIMD Matrix multiplication approaches and I persistently get this error:
void mmul_sse_nsize(const float * a, const float * b, float * r, int size) {
__m128 a_line, b_line, r_line;
int bound = size*size;
int rows = size;
[Code] ....
The code almost never throws the error when matrices are size NxN, N =4.
Also, I have a 4 core laptop with 2 GB RAM and I am using VS2013.
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Dec 12, 2014
I am trying to read two matrices from individual .txt file, and later trying to multiply them. But I am unable to succeed.
Here is the code.
#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
// Here starts the main
int main()
{ // The two input values
FILE *inputFile1;
FILE *inputFile2;
[Code] .....
I am able to get only the first values as the output. The first matrix is 5x3, and the second one is a 3x3 matrix.
Matrix 1
1 2 3
4 5 6
7 8 9
10 11 12
Matrix 2
1 2 3
4 5 6
7 8 9
The output which I am getting is
Enter File name of matrix #1 - with extention - : matrix1.txt
Enter File name of matrix #2 - with extention - : matrix2.txt
Rows1 = 1 Cols1 = 2
Rows2 = 1
Cols2 = 2Cant multiply those two matrices
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Oct 31, 2014
I am writing a brute force implementation of matrix multiplication:
Header file:
vector<vector<int> > matrix_multiplication(vector <vector<int> >& a, vector <vector<int> >& B)/>/>/>;
Source file:
vector<vector<int> > matrix_multiplication(vector <vector<int> >& a, vector <vector<int> >& B)/>/>/>{
int n = a.size();
vector< vector <int> > c (n , vector<int> (n));
for (int i =0 ; i<n ; i++){
for (int j =0 ; j < n ; j++){
for (int k ; k < n ; k++){
c[i][j] = a[i][k] + b[k][j];
[Code] ....
I keep on getting occasional seg faults />/>. I can't see why.
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Aug 31, 2014
How to write matrix multiplication (without using arrays) in C ....
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Apr 12, 2013
So basically I have to tell the user to input data and i use a for loop:
for (i=0; i< 3; i++)
cin >> p[i][0],p[i][1], p[i][2];
Now for the confusing part is, what do i put in the nested for loops to multiply them and output them so it looks something like
matrix p,r1: # # #
" ",r2: " "
" " " "
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Nov 11, 2013
I would like to know how could I make multiplication of matrix called betrix in this code:
Code:
printf("transposed matrix:
");
int trantrix[size][size]; //transposed matrix
for(i=0;i<size;i++) {
for(j=0;j<size;j++) {
trantrix[i][j] = matrix[j][i];
printf("%d ",trantrix[i][j]);
[Code] ......
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Oct 9, 2013
I just started Linear Algebra for my programming degree and to full understand everything I want to put it into code and make my own "matrix calculator." I have all the theory but I am having issues keeping the matrix variable and moving it around the class' functions to create it and output it. Once I know I have it saved I think I can get the addition/multiplication to work. Here is the code I have so far:
#include <string>
#include <iostream>
using namespace std;
class matrix {
[Code] ....
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Mar 9, 2014
I have a program matrix multiplication but it work not for big arrays. n should be bis 200.
#include <iostream>
#include <time.h>
#include <cstdlib>
[Code]....
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Mar 24, 2014
I am actually working on IEEE Arithmetic especially the IEEE 754 specification where the IEEE double only have 53 bits of precision. I am working on Z/nZ matrix multiplication that works on 53 bits specs. How to write a matrix multiplication algorithm that works well on 53 bits IEEE precision standard.
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Oct 5, 2014
I have a problem with dynamic massive. My task was to find the multiplication of positive matrix elements with using indexes and seperated compiling.
Compiler doesn't warn me about any mistake, but result is not right, it is even not a number.
Header.h
#include <iostream>
#include <math.h>
using namespace std;
float multi(int k, int t, float **p);
[Code] ....
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Oct 1, 2014
I've been trying to get my matrix multiplication program to run a few different ways. My assignments wants me to run it statically using chunks, but we're not supposed to use OpenMPs scheduler. So I'm not sure how that's possible. And secondly, we have to run it dynamically using locks/unlocks.
Static (not sure how to implement chunk)
#pragma omp section
{
printf("Thread %d doing matrix mult", threadID);
if (matrixAcols != matrixBrows) {
cout << "Error, operation not possible" << endl;
[Code]....
The code will run for a long time too. It uses as many threads as we tell it to but it never speeds up the results.
Quote
Thread 2 doing matrix mult
Thread 4 doing matrix mult
Thread 2 doing matrix mult
Thread 4 doing matrix mult
Thread 2 doing matrix mult
Thread 4 doing matrix mult
Thread 2 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
Thread 4 doing matrix mult
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Apr 30, 2014
I wrote program for Sequential matrix multiplication .But after execution for any input value( ex. 100,150,400) it shows the execution time is 0.000 msec.
#include <stdio.h>
#include <math.h>
#include <sys/time.h>
void print_results(char *prompt, int N, float *a);
int main(int argc, char *argv[])
[Code] ......
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Apr 30, 2014
I wrote a sequential matrix multiplication program in c.
After execution i get error like
./mul.c: line 11: syntax error near unexpected token `('
./mul.c: line 11: `int main(){'
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define wA (30 * 16)
#define wB (50 * 16)
#define hA (80 * 16)
#define hB wA
#define wC wB
[Code] ....
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Mar 24, 2012
Code:
#include <iostream>
#include <istream>
#include <fstream>
#include <vector>
[Code]....
Why is it reading in nothing for the arrays, and also making the size of the total thing the total number of numbers? It should have a size of 2, not 5.
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Aug 20, 2014
I want to convert the matrix to vector and vice verse.
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Jul 2, 2013
i have 12 vectors of size 1*150 (1 row 150 columns)
i want to merge all these 12 vectors to a matrix of size 12 *150 (12 row 150 columns)
all vectors are of same size 1* 150 andAll of them have to join into a matrix of size 12* 150
say vectors are (A1 A2 ... A12) TO a single matrix A(size 2 * 150) I AM USING MATLAB
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Mar 27, 2013
i want to know how i can solve this question? do i need to create a class or write the program codes.
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Feb 27, 2012
I want to assign a matrix to submatrix of a bigger matrix.
ublas::matrix<int> A(8,5);
ublas::matrix<int> B(2,5);
for(size_t i=0;i<A.size1();++i)
for(size_t j=0;j<A.size2();++j)
A(i,j)=i*A.size2()+j+1;
for(size_t i=0;i<B.size1();++i)
for(size_t j=0;j<B.size2();++j)
B(i,j)=i*B.size2()+j+5;
ublas::matrix_range<ublas::matrix<int> > a(A,ublas::range(0,2),ublas::range(0,5));
a=B;
and it works.
but if the matrix is compressed_matrix type, there's something with it. the error log as below:
Check failed in file boost_1_48_0/boost/numeric/ublas/detail/matrix_assign.hpp at line 1078:
detail::expression_type_check (m, cm)
terminate called after throwing an instance of 'boost::numeric::ublas::external_logic'
what(): external logic
Aborted
I'm not sure this is a bug or not.
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May 25, 2014
I have to prepare a project. But I don t know how can I do this. Program will find a matrix P for a square matrix A such that P^-1 A P ....
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Oct 4, 2014
3 3
2 1 3 2 3
1 0 2
1 2 6
First line shows row and column number
First index of the second line tells the number of non-zero entries of the first row and second index tell the column number where the non zero entry is placed
for 1st row of matrix:
non-zero entries=2
column number=1
non-zero entry=3
column number=2
non-zero entry=2
covert this in the given form
0 3 3
2 0 0
0 0 6
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Mar 28, 2013
I want to set an integer to zero when it easy equal to another integer, but it seems that the program for some reason won't set the integer to zero. Here is the example of that code:
#include <iostream>
using namespace std;
int main () {
int n = 2;
int r = 2;
if(n==r)
n++;
r*0;
cout << " n is " << n << endl;
cout << " r is " << r << endl;
}
What am I doing wrong, it should say that "n is 3" and "r is 0".
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Dec 30, 2014
I want to declare a 2D 4*4 array, and fills the array with the multiplication table of an integer x from the user, for example: x*1,x*2,x*3, ....., x*16 and how to pass that array to a function to print the array and to another function that swaps a column with another column chosen by the user.
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