FFT Multiplication (HP-48G/GX/G+)

[Raymond Del Tondo]

Hi,

(02-10-2014 10:02 PM)Gerson W. Barbosa Wrote:  

(02-10-2014 09:25 PM)Gerson W. Barbosa Wrote:  . My HP-48GX is about 50% slower than the HP-71B when multiplying two 512-digit numbers (173 seconds versus 117 seconds).

Two 256-digit numbers, actually, giving a 512-digit result. Sorry for the mistake.

You could speed up things by trying to avoid object type changes where possible.

The snippet below shows some time-consuming actions from your code.

(02-10-2014 10:02 PM)Gerson W. Barbosa Wrote:  

Code:


  START 0 +
  NEXT SWAP ROT 1
ROT
  START 0 +
  NEXT 

OBJ\-> 

1 \->LIST

\->ARRY

If you work with arrays anyway, you could try to avoid building lists. Creating and decomposing lists is very time-consuming.
If possible, meta obs are recommended.

I didn't dive into the code too deeply, but I'm sure the functionality can be made faster on an HP 48GX than any code giving the same results on an HP-71B;-)