[Lush-users] little fix for idx-flatten

[Fabian <fb...@t-...>]

Hi all,

there is a little bug in idx-flatten, when you use it with a negative
argument. For example:

;;define:
(setq a (idx-reshape (arange (* 12 57 12 12 3)) '(12 57 12 12 3)))
= ::Index:DoubleStorage:<12x57x12x12x3>

;;now you get:
(idx-flatten a -2)
*** index-reshape! : number of elements must be the same with new
shape : 295488
Debug toplevel [y/N] ?

------------
Fix:
in file src/index.c, function index_flatten
line 3716, replace

for (int i=IND_NDIMS(ind)-2; i>=r-1; i--)
   IND_DIM(shp, r-1) *= IND_DIM(ind, i);
for (int i=r-2; i>=0; i--)
   IND_DIM(shp, i-r+2) = IND_DIM(ind, i);

with:

for (int i=0; i<=r-2;i++) 
  IND_DIM(shp, i) = IND_DIM(ind, i);
for (int i=r-1; i<=IND_NDIMS(ind)-2;i++) 
  IND_DIM(shp, r-1) *= IND_DIM(ind, i);

------------


;;now it works;
(mapfor (i -4 4 1) (shape (idx-flatten a i)))
;;gives:
((295488) (12 24624) (12 57 432) (12 57 12 36)
(12 57 12 12 3)
(684 12 12 3) (8208 12 3) (98496 3) (295488))


with best regards
Fabian