41Z Routine of the week: DFT

[Ángel Martin]

Good catch Greg, thanks for the warning. Indeed using "E" is not a good idea if register P is also used for storage, I had completely forgotten about that... since I moved to the all-MCODE version in the updated module attached ;-)

So just change the "E" to a "1" and the program should work fine.

Here's an alternative FOCAL version that should always work, just to close this issue. It does the intermediate multiplication in-situ so registers R00 and R01 are free to use now.

Code:

01    LBL "ZDFT"
02    CF 01
03    GTO 00
04    LBL "ZIDFT"
05    SF 01
06    LBL 00
07    STO 00
08    E3/E+
09    STO M(5)
10    LBL 01
11    VIEW M(5)
12    RCL 00
13    STO N(6)
14    E3/3+
15    STO O(7)
16    RCL 5(M)
17    INT
18    ST+  N(6)
19    E
20    -
21    PI
22    *
23    ST+ X(3)
24    RCL 00
25     /
26    STO 01
27    CLZ
28    ZSTO IND N(6)
29    LBL 02
30    RCL 0(7)
31    INT
32    E
33    -
34    RCL 01
35    *
36    FC? 01
37    CHS
38    E
39    P-R
40    ZRC* IND O(7)
41    ZST+  IND N(6)
42    ISG O(7)
43    GTO 02
44    FC? 01
45    GTO 00
46    ZRCL IND 01
47    RCL 00
48    ST/ Z
49     /
50    ZSTO IND 01
51    LBL 00
52    ISG M(5)
53    GTO 01
54    END

Latest revision of the 41Z deluxe is attached.


Cheers,
Ángel