Method: AppMath::Mat#*

Defined in:
lib/linalg.rb

#*(v) ⇒ Object

Multiplication of a Mat with either a Mat, Vec, or Numeric



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# File 'lib/linalg.rb', line 926

def *(v)
  d1 = dim1
  fail "dim1 == 0" if d1.zero?
  d2 = dim2
  fail "dim2 == 0" if d2.zero?
  zero=@x[0].x[0].to_0
  if v.is_a?(Mat)
    d3 = v.dim1
    fail "dimenson mismatch" unless d3 == d2
    d4 = v.dim2
    fail "dim4 == 0" if d4.zero?
  # we better produce the d1 row-vectors in turn

    a = Array.new(d1)
    for i in 0...d1
      vi = Vec.new(d4,zero)
      for j in 0...d4
        vij = zero
        for k in 0...d2
          vij += @x[i].x[k] * v.x[k].x[j]
        end
        vi.x[j] = vij
      end
      a[i] = vi
    end
    res = Mat.new(a)
  elsif v.is_a?(Vec) 
    d3 = v.dim
    fail "dimenson mismatch" unless d3 == d2
    res = Vec.new(d1,zero)
    for i in 0...d1
      vi = zero
      for j in 0...d2
        vi += @x[i].x[j] * v.x[j]
      end
      res.x[i] = vi
    end
  elsif v.is_a?(Numeric) # multiplication with scalar

    res = clone
    for i in 1..d1
      res[i] *= v
    end
  else
    fail "can't multiply with this object"
  end
  res
end