From wscott%EN.ECN.PURDUE.EDU@VM1.NoDak.EDU Wed Feb 21 09:34:51 1990 Date: Wed, 21 Feb 90 00:16:06 -0500 Reply-To: HP-28 - HP-28C and HP-28S Calculators Sender: HP-28 - HP-28C and HP-28S Calculators From: Wayne H Scott Subject: new Bessel X-To: HP-28@VM1.NoDak.EDU To: Multiple recipients of list HP-28 This is a new version of the bessel function program. It is faster by using stack functions and it fixes one bug in the previous posting. This is a function I wrote to aid in my study of FM signal modulation. It computes the bessel function. It expects n and x to be on the stack and it returns the result of the bessel function. Note it is recursive so it should be named J or change the one reference to this name within the program. Works on HP28 or HP48 Jn << -> n x << << IF n 0 < THEN n NEG x Jn n 2 MOD 2 * 1 - * NEG ELSE IF x 0 == THEN n 0 == ELSE 17.1032 .2639 n * + .6487 x ABS * + .0018 n * x ABS * - .6457 n x ABS MAX * + .5 + FLOOR 2 / CEIL 2 * 1.e-50 0 -> m tiny bn << tiny 2 * 0 0 tiny m 1 - 0 FOR k ROT DROP 2 k 1 + * OVER * x / 3 PICK - IF k n == THEN DUP 'bn' STO END if k 0 == THEN DUP 5 ROLL + 4 ROLLD ELSE IF k 2 MOD 0 == THEN DUP 2 * 5 ROLL + 4 ROLLD END END -1 STEP 3 DROPN bn SWAP / >> END END >> >> If entered on a HP-48sx checksum=#9519h 555.5 bytes Ported from MatLab librarys. _______________________________________________________________________________ Wayne Scott | INTERNET: wscott@en.ecn.purdue.edu Electrical Engineering | BITNET: wscott%ea.ecn.purdue.edu@purccvm Purdue University | UUCP: {purdue, pur-ee}!en.ecn.purdue.edu!wscott