MatRepl

• is a Matrix
• and a repl: Read–Eval–Print Loop, where Print is doing operations on vectors and matrices in a graphic environment
• written in vanilla javascript (ES6)

The repl has the following syntax (It's work in progress, new capabilities will be added)

• arithmetic expressions:
  • add, subtract, divide, multiply
• variable declaration eg: a= ...
• vector(1,2,3,4) adds a vector

  • > vector@0{x0:1, y0: 2, x:3, y:4}

• remove(x) removes bindings (when it's an object (eg vector), removes it from the matrix)
• remove(@x) removes an object using it's assigned index
• method calls:
  • a = vector(0,0,12,1)

  > vector@0{x0:1, y0: 2, x:12, y:1}

  • a.type()

  > vector

• property lookup
  • a.x+1

  > 13

• drag vectors using the mouse pointer. You can change the vector arrows visually
• lazy evaluation. The difference between c = a+b and c = "a+b" is that the latter assigns to c a parsed expression that can always be evaluated later. When you apply lazy evaluation and later update a, the value for c will be reevaluated automatically. (NB automatic reevaluation is not yet implemented). Combined with vector dragging, you can get an intuition for vector addition.

To run locally

• make sure you have node/npm
• cmdline: npm run start
• enter the following:

  a=vector(0,0,0.5,0.5)
  b=vector(0,0,-1,1)
  c=a+b
  

• and press enter
• or type help()