Typed matrix dimensions?

[AlexMouton]

Hi Jos, et al.
Is there a way for me to enforce the dimensionality of a matrix in a typed function?
I am interested in specifying vectors/positions specifically, and would rather not have to check those repeatedly.

I see theres a hot new version, so excuse me if this is now dated.

Thanks
Alex Mouton

[josdejong]

That's an interesting question. There is no provisioning in typed-function to specify the size of a matrix, but you could introduce a new datatype yourself for this, something like:

const math = require('mathjs')

// define a new type, which checks whether a value is a Matrix with size 3x2
math.typed.types.push({name:'Matrix3x2', test: function (x) {
  if (!x || !x.isMatrix) {
    return false
  }
  const size = x.size()
  return size.length === 2 && size[0] === 3 && size[1] === 2
}})

// create a typed function using this new data type
const myFunction = math.typed('myFunction', {
  'Matrix3x2, Matrix3x2': function (a, b) {
    return math.add(a, b)
  }
})

const a1 = math.matrix([[1,2], [3,4], [5,6]])
const b1 = math.matrix([[7,8], [9,10], [11,12]])
const result1 = myFunction(a1, b1)
console.log(result1.toString()) // [[8, 10], [12, 14], [16, 18]]

const a2 = math.matrix([[1,2], [3,4], [5,6]])
const b2 = math.eye(3, 3)
const result2 = myFunction(a2, b2)
// TypeError: Unexpected type of argument in function myFunction
//            (expected: Matrix3x2, actual: Matrix, index: 1)

Would something like that work for you?

[AlexMouton]

I think so. Ill give it a try.
Thanks
A

[gwhitney]

Since this was a question and was answered, moving to Q&A.