Definition

https://www.mathsisfun.com/algebra/matrix-introduction.html

How to do Multiplication

Online calculator

C implementation 

/* Multiplying matrix a and b and storing in array mult. */    for(i=0; i

/*mat(r*c) *mat(r),v will have k rows,1 column

for(i=0;i<k;i++)

for(j=0;j<k;j++)

   v[i]+=mat[i][j]*v2[j];

*/

/*v1 has k columns and 1 row,v has 1 coumn,k rows,result will have one

row,one column,so only using a variable to store is ok

for(i=0;i<k;i++)

      result=result+v1[i]*v[i];

*/