Little problem(s) July 2022

[Thomas Klemm]

This is a solution for #1 for the HP-42S:

Code:

00 { 38-Byte Prgm }
01▸LBL "FIND"
02 GTO 01
03▸LBL 00
04 RCL IND ST Y
05 RCL+ IND ST Y
06 RCL- 00
07 X=0?
08 GTO 02
09 R↓
10 DSE ST X
11 GTO 00
12 R↓
13 DSE ST X
14▸LBL 01
15 ENTER
16 DSE ST X
17 GTO 00
18▸LBL 02
19 R↓
20 END

But it should work with the HP-41C as well after minor adjustments.
The \(\text{target}\) and the values of the list \(\{a_1, a_2, \cdots, a_n\}\) are expected in the registers:

R00: \(\text{target}\)
R01: \(a_1\)
R02: \(a_2\)
…
Rnn: \(a_n\)

Example

17 STO 00

2 STO 01
7 STO 02
11 STO 03
15 STO 04

4
XEQ "FIND"

4
1