CODEWITHSUNDEEP
c++armadillo
Achamyeleh Dagnaw
Achamyeleh Dagnaw

Reputation: 89

element wise vector or matrix multiplication in Armadillo C++

#include<iostream>
#include<armadillo>
using namespace std;
using namespace arma;

int main()
   {    
      vec x = (1.0/5) * ones<vec>(N); //x is N sized uniformly distributed vector 
      vec xold(5); 
      mat v = randu<mat>(3,3);
      mat b =randu<mat>(3,3);
     mat c =  v .* b; //element-wise matrix multiplication
     xold = x .* x; // element-wise vector multiplication
 }

 //----------------------------this is the error message --------------------------------
/*
  In function ‘int main()’:
  SimilarityMatrix.cpp:182:17: error: ‘b’ cannot be used as a member pointer, since it is of      type ‘arma::mat {aka arma::Mat<double>}’
mat c =  (v.*b);
             ^

SimilarityMatrix.cpp:183:14: error: ‘x’ cannot be used as a member pointer, since it is of type ‘arma::vec {aka arma::Col}’ xold = x .* x; ^ */ //I would appreciate any immediate response.

Upvotes: 3

Views: 12522

Answers (1)

mtall
mtall

Reputation: 3620

It's explained in the Armadillo documentation.

See the section on operators, which states that % is used for element-wise multiplication:

mat c =  v % b;

Upvotes: 12

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