ln and e^x on the 16C?

[Gerson W. Barbosa]

(03-22-2016 05:44 PM)Dave Britten Wrote:  If I could add some programs to calculate ln(x) or e^x, then I could at least get powers and roots in place for those occasions when it's needed. Before I go reinventing the wheel (with a clumsy Taylor series or something), has anybody already tackled this problem on the 16?

If you haven’t come up with anything better and you’re still interested, you might want to try this, if reduced accuracy isn’t a problem:

01 LBL A ; ln(x)
02 1
03 EEX
04 CHS
05 3
06 CF 1
07 1
08 +
09 STO I
10 CLx
11 LASTx
12 x<>y
13 x<=y
14 GSB 2
15 LBL 0
16 √x
17 RCL I
18 x>y
19 GTO 1
20 Rv
21 x<>y
22 ENTER
23 +
24 x<>y
25 GTO 0
26 LBL 1
27 Rv
28 ENTER
29 +
30 1
31 -
32 √x
33 x<>y
34 ENTER
35 +
36 *
37 LASTx
38 -
39 F? 1
40 CHS
41 RTN
42 LBL 2
43 SF 1
44 1/x
45 RTN
46 LBL B ; e^x
47 1
48 3
49 STO I
50 Rv
51 8
52 1
53 9
54 2
55 +
56 LASTx
57 /
58 ENTER
59 *
60 1
61 +
62 2
63 /
64 LBL 4
65 ENTER
66 *
67 DSZ
68 GTO 4
69 RTN

Examples:


2 GSB A -> 0.693148000
GSB B -> 2.000013165

12345 GSB A -> 9.42101000
GSB B -> 12345.12104

6.789 EEX 79 GSB A -> 183.8196
GSB B -> 6.687315E79

0.12345 GSB A -> -2.091921000
GSB B -> 0.123449622

230 GSB B -> 7.496895E99
GSB A -> 229.9703000

1 GSB A -> 0.000000000
GSB B -> 1.000000000
GSB B -> 2.718292170
GSB B -> 15.15444181
GSB A -> 2.718294000
GSB A -> 1.000005000
GSB A -> 0.000005000

0.693147181 CHS GSB B -> 0.50000016

0 GSB A -> Error 0

2 CHS GSB A -> Error 0