matrix

Implementation of Matrix and Vector Objects in Crystal

Progress

• Matrix class initiated
• row and col functionality implemented

todo

• decide whether to use struct or class
• Matrix.diagonal(9, 5, -3)
• Matrix.scalar(dim=2, entries=5)
• Matrix.zero(row_count, column_count = row_count)
• Matrix.vstack(x, *matrices)
• Matrix.hstack(x, *matrices)
• Matrix.combine(*matrices) { |*elements| ... }
  • x = Matrix[[6, 6], [4, 4]]
  • y = Matrix[[1, 2], [3, 4]]
  • Matrix.combine(x, y) {|a, b| a - b} # => Matrix[[5, 4], [1, 0]]
• initialization of matrix with empty rows and cols
• fill matrix with zeros (or else)
• collect(which = :all, &block)
  • use case
  • :all (default): yields all elements
  • :diagonal: yields only elements on the diagonal
  • :off_diagonal: yields all elements except on the diagonal
  • :lower: yields only elements on or below the diagonal
  • :strict_lower: yields only elements below the diagonal
  • :strict_upper: yields only elements above the diagonal
  • :upper: yields only elements on or above the diagonal
  • Matrix[ [1,2], [3,4] ].collect { |e| e**2 }
    • __1 _4
    • __9 16
• Matrix.each :byrow, :bycol, :all etc similar to collect
  • use case
• get value by row and col-index
• Error handling (raise)
• Tests:
  • symmetric?
  • diagonal?
  • square?
  • empty?
  • has_na?
  • has_zero?
  • is_identity?
  • is_lower?
  • is_upper?
  • hermitian?
  • normal?
• == for Vector and Matrix
• mult(*) for Vector and Matrix
• division (/) (multiplication by the inverse) for Vector and Matrix
  • Matrix[[7,6], [3,9]] / Matrix[[2,9], [3,1]]
  • => -7 _1
  • ___ -3 -6
• add(+) for Vector and Matrix
• sub(-) for Vector and Matrix