method

*

v1_9_3_125 - Show latest stable - 0 notes - Class: Matrix

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What's this?

*(m) public

Matrix multiplication.

Matrix[[2,4], [6,8]] * Matrix.identity(2)
  => 2 4
     6 8

Show source

# File lib/matrix.rb, line 802
  def *(m) # m is matrix or vector or number
    case(m)
    when Numeric
      rows = @rows.collect {|row|
        row.collect {|e| e * m }
      }
      return new_matrix rows, column_size
    when Vector
      m = Matrix.column_vector(m)
      r = self * m
      return r.column(0)
    when Matrix
      Matrix.Raise ErrDimensionMismatch if column_size != m.row_size

      rows = Array.new(row_size) {|i|
        Array.new(m.column_size) {|j|
          (0 ... column_size).inject(0) do |vij, k|
            vij + self[i, k] * m[k, j]
          end
        }
      }
      return new_matrix rows, m.column_size
    else
      return apply_through_coercion(m, __method__)
    end
  end

*

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