[VA] SRC #014 - HP-15C & clones: Accurate NxN Determinants

[Werner]

The Bird algorithm (thanks, J-F) implemented for the 42S.
I made two changes:
- negate the input matrix A once
- shrink the matrix B (remove a row) at every step, as the last row is always filled with zeroes.
O, and stack-only. Of course.

00 { 79-Byte Prgm }
01▸LBL "BIRD"
02 ENTER
03 +/-
@
04▸LBL 03
05 X<>Y
06 DIM?
07 X<> ST L @   [B]     I       -[A]
08 EDIT
09 CLX
10 SIGN
11 X=Y? @ quit when B is a single row
12 GTO 00
13 X<>Y
14 ENTER @      I       I       1       -[A]
15 STOIJ
16 R^
17 RCLEL
18 +/- @        SUM     -[A]
19 J-
20 1
21 ENTER
@               X       Y       Z       T       I,J
22▸LBL 02 @     1       N-I     SUM     -[A]    I,I-1
23 NEWMAT @     [0]     SUM     -[A]    -[A]
24 PUTM
25 I-
26 RCLEL
27 +/-
28 X<> ST Z
29 STOEL
30 STO+ ST Z
31 R↓
32 DIM?
33 STO+ ST Y
34 J-
35 FC? 76
36 GTO 02
@ 
37 DELR
38 EXITALL
39 R^
40 STO× ST Y
41 GTO 03
@ 
42▸LBL 00
43 RCLEL
44 ENTER
45 EXITALL
46 R↓
47 END

Cheers, Werner