Approximates real numbers as fractions using continued fraction
algorithm. With sufficiently high accuracy, rational numbers should
get exact solutions.

Inputs:
X: decimal to convert
ACC: precision level

Outputs:
Y: numerator
X: denominator
LASTX: X input

Registers:
00: X input
01: current convergent
02: current coefficient
03: previous numerator
04: current numerator
05: previous denominator
06: current denominator


00 { 79-Byte Prgm }
01>LBL ">FRAC"
02 INPUT "ACC"
03 Rv
04 CLRG
05 STO 00
06 1
07 STO 04
08 STO 05
09 RCL 00
10>LBL A
11 ENTER
12 IP
13 STO 02
14 -
15 X!=0?
16 1/X
17 STO 01
18 RCL 02
19 RCL× 06
20 RCL+ 05
21 X<> 06
22 STO 05
23 RCL 02
24 RCL× 04
25 RCL+ 03
26 X<> 04
27 STO 03
28 RCL 00
29 RCL 04
30 RCL/ 06
31 -
32 ABS
33 RCL "ACC"
34 X>=Y?
35 GTO B
36 RCL 01
37 GTO A
38>LBL B
39 RCL 00
40 STO ST L
41 RCL 04
42 RCL 06
43 END