matrice python condensée au carré
import math
def calc_row_idx(k, n):
return int(math.ceil((1/2.) * (- (-8*k + 4 *n**2 -4*n - 7)**0.5 + 2*n -1) - 1))
def elem_in_i_rows(i, n):
return i * (n - 1 - i) + (i*(i + 1))//2
def calc_col_idx(k, i, n):
return int(n - elem_in_i_rows(i + 1, n) + k)
def condensed_to_square(k, n):
i = calc_row_idx(k, n)
j = calc_col_idx(k, i, n)
return i, j
Better Butterfly