dot

Purpose

Returns a scalar dot product of the columns of two matrices.

Format

z = dot(x, y)
Parameters:
  • x (Nx1 vector or NxK matrix) – first matrix.
  • y (Nx1 vector or NxK matrix) – second matrix, y.
Returns:

z (scalar or Kx1) – The dot product of x and y.

Examples

Basic usage

// Create two 4x1 column vectors
x = { 5,
      9,
      3,
      4 };

y = { 9,
     -6,
      8,
      1  };

// Compute dot product
z = dot(x, y);

print  "z = " z;

After the code above:

z = 19

Dot product of an Nx1 vector and Nx2 matrix

// Create 4x1 vector
x = { 5,
      9,
      3,
      4 };

// Create 4x2 matrix
y = { 9  8,
     -6  4,
      8  3,
      1 -2 };

// Compute dot product
z = dot(x, y);

print  "z = " z;

After the code above:

z = 19
    77

Dot product of the corresponding columns of two matrices

// Create two 4x2 matrices
x = { 5 1,
      9 3,
      3 8,
      4 2 };

y = { 9  8,
     -6  4,
      8  3,
      1 -2 };

// Compute dot product
z = dot(x, y);

print  "z = " z;

After the code above:

z = 19
    40

Remarks

x and y must have the same number columns, or one of them must only have a single column.

See also

Functions crossprd(), norm()