TriL

Return a copy of a matrix with elements above the k-th diagonal zeroed. Lower triangular matrix.

matrix matrix::Tril(
const int ndiag=0 // index of diagonal
);

Parameters

ndiag=0

[in] Diagonal above which to zero elements. ndiag = 0 (the default) is the main diagonal, ndiag < 0 is below it and ndiag > 0 is above.

Return Value

Array with its lower triangle filled with ones and zero elsewhere.

MQL5 example:

   matrix a={{1,2,3},{4,5,6},{7,8,9},{10,11,12}};
   matrix b=a.TriL(-1);
   Print("matrix b \n",b);

  /*
  matrix_c
  [[0,0,0]
  [4,0,0]
  [7,8,0]
  [10,11,12]]
  */

Python example:

import numpy as np

a=np.tril([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1)

[[ 0  0  0]
[ 4  0  0]
[ 7  8  0]
[10 11 12]]