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# Multiplication of the matrix to the vector. C++

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created class matrix and class vector. How to implement a multiplication function on each other?

``````class matrix
{
Public:
INT ** ARR;
int rows;
int columns;
Public:
Matrix () {};
Matrix (int rows, int columns)
{
this- & gt; rows = rows;
this- & gt; columns = columns;
arr = new int * [rows];
for (int i = 0; i & lt; rows; i ++)
{
arr [i] = new int [columns];
}
for (int i = 0; i & lt; rows; i ++)
{
For (int j = 0; j & lt; columns; j ++)
{
Arr [i] [j] = 0;
}
}
}
};
Class Vector
{
Private:
int * vec;
int size;
Public:
Friend Matrix;
Vector (Int Size)
{
This- & gt; Size = Size;
Vec = New int [Size];
for (int i = 0; i & lt; size; i ++)
{
VEC [i] = 0;
}
}
};
``````

Such an action is possible if there is some matrix Matrix [M, N] and some vector VEKTOR [N], the number of elements of which is equal to the number of lines of the matrix. As a result, we obtain the vector new_vektor [n], the first element of which is the amount of the works of the first string of the Matrix [M, n] array of the Matrix [N] array elements, the second element is the amount of the elements of the second line of the MATRIX array [m, n] on the elements Array Vektor [n], etc.

Not knowing what kind of classes are for the matrix and vector, I can only offer a solution for arrays:

``````void matrmultiply (int n, int m, float * matrix, float * vektor, float * res) // if integer values ​​are needed, can be replaced by int
{
for (int i = 0; i & lt; n; i ++)
{
Float temp = 0;
for (int j = 0; j & lt; m; j ++)
{
TEMP + = MATRIX [I * M + J] * VEKTOR [J];
}
res [i] = temp;
}
}}
``````

And then implement a similar solution for your classes.

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