frob.js
function frob(a) {
  return Math.sqrt(
      a[0]*a[0]
    + a[1]*a[1]
    + a[2]*a[2]
    + a[3]*a[3]
    + a[4]*a[4]
    + a[5]*a[5]
    + a[6]*a[6]
    + a[7]*a[7]
    + a[8]*a[8]
  )
}
function frob(a) {
  return Math.sqrt(
      a[0]*a[0]
    + a[1]*a[1]
    + a[2]*a[2]
    + a[3]*a[3]
    + a[4]*a[4]
    + a[5]*a[5]
    + a[6]*a[6]
    + a[7]*a[7]
    + a[8]*a[8]
  )
}
function frob ( a ) { return Math . sqrt ( a [ 0 ] * a [ 0 ] + a [ 1 ] * a [ 1 ] + a [ 2 ] * a [ 2 ] + a [ 3 ] * a [ 3 ] + a [ 4 ] * a [ 4 ] + a [ 5 ] * a [ 5 ] + a [ 6 ] * a [ 6 ] + a [ 7 ] * a [ 7 ] + a [ 8 ] * a [ 8 ] ) }
Returns Frobenius norm of a mat3

@alias mat3.frob
@param {mat3} a the matrix to calculate Frobenius norm of
@returns {Number} Frobenius norm
Returns Frobenius norm of a mat3