RCL Σ+

[Dave Britten]

Somehow I've gone all this time without realizing that RCL Σ+ can be used to recall ΣX and ΣY to X and Y on quite a few models. Which models support this? I've only had a chance to check a few so far.

45: I think this was a yes, I'll have to double check
80: No (no stat regs, only very basic one-variable summations that work entirely on the stack)
65: No (no built in stat functions; what about the 67 which has them?)
25: Haven't tested yet, ROM was really packed to the brim so it might have been left out
38E/C: No
41C: No (Σ+ is a shortcut for 01 with STO/RCL/GTO/XEQ)
12C: No
15C: Yes
16C: No (no summation/stat functions)
27S: No (list-based stats, not RPN, no Σ+ key)
32S, 32SII: No (Σ+ becomes the F key for STO/RCL/GTO/XEQ)
42S: No (Σ+ becomes a menu key for the variable menu when STO/RCL is active, and TOP.FCN can't be used to get to Σ+ while STO/RCL are pending); SUM function does the same thing but overwrites X and Y without lifting the stack

Do any support STO Σ+ to store two values directly into the ΣX and ΣY registers?

[Thomas Okken]

(02-07-2020 01:37 PM)Dave Britten Wrote:  Somehow I've gone all this time without realizing that RCL Σ+ can be used to recall ΣX and ΣY to X and Y on quite a few models. Which models support this?

25/25C: No
19C/29C: Yes
67/97: Yes
41C: No (With card reader: Yes, 7RCLΣ)
42S: Yes (SUM)

(02-07-2020 01:37 PM)Dave Britten Wrote:  Do any support STO Σ+ to store two values directly into the ΣX and ΣY registers?

Not as far as I know, but I'm prepared to be surprised.

[teenix]

(02-07-2020 01:37 PM)Dave Britten Wrote:  Somehow I've gone all this time without realizing that RCL Σ+ can be used to recall ΣX and ΣY to X and Y on quite a few models. Which models support this? I've only had a chance to check a few so far.

45: I think this was a yes, I'll have to double check

Yes, the 45 does.

cheers

Tony

[pinkman]

What about 35s ? I gave mine to my son...

[rprosperi]

(02-07-2020 11:17 PM)pinkman Wrote:  What about 35s ? I gave mine to my son...

Nope.

[Rogier]

33E and 11C support this. I used it regularly, because it saves a program line when you want to recall 2 memories.

Sto Σ+ doesn't work. Neither do Sto π and Rcl π. I tried.

[Carsen]

Hi Dave.

When I use the RCL Σ+ on my 12C, it does not recall the ΣX and ΣY. It simply performs Σ+. Does your 12C actually perform the RCL Σ+ function? Or is it an error?

Best,
- Carsen

[teenix]

(02-10-2020 07:47 AM)Carsen Wrote:  Hi Dave.

When I use the RCL Σ+ on my 12C, it does not recall the ΣX and ΣY. It simply performs Σ+. Does your 12C actually perform the RCL Σ+ function? Or is it an error?

Best,
- Carsen

It is probably not supported and the [RCL] is cancelled when you press the [Σ+].

cheers

Tony

[Didier Lachieze]

According to the op code tables here, RCL Σ+ is supported on:

• HP-29C (0F), HP-33C (9F), HP-34C (5A), HP-67/97 (0F), HP-11C (A6), HP-15C (A7)
  

but not on:

• HP-38C, HP-12C, HP-16C

[Dave Britten]

I could have sworn it worked on my 12C, but I could be imagining things. I do have quite a few Voyagers accumulating these days...

[Joe Horn]

Strangely, RCL Σ+ doesn't push its values onto the stack the same way on all models. Some directly overwrite X and Y, leaving the previous values of Z and T in place (e.g. the HP-55, 67, and 29), while others first lift the previous values of X and Y into Z and T (e.g. the HP-45, 33E and 34C).

Did RCL Σ+ disable stack lift on any models? That would seem like a crazy thing to do, but I seem to recall that some model did so, which tells me that it must be true, because "The curse of aging is a sort of creeping infallibility."

[Thomas Okken]

(02-10-2020 03:49 PM)Joe Horn Wrote:  Strangely, RCL Σ+ doesn't push its values onto the stack the same way on all models. Some directly overwrite X and Y, leaving the previous values of Z and T in place (e.g. the HP-55, 67, and 29), while others first lift the previous values of X and Y into Z and T (e.g. the HP-45, 33E and 34C).

Did RCL Σ+ disable stack lift on any models? That would seem like a crazy thing to do, but I seem to recall that some model did so, which tells me that it must be true, because "The curse of aging is a sort of creeping infallibility."

On the machines I'm familiar with, RCL Σ+ (a.k.a. SUM on the HP-42S) overwrite X and Y and don't lift the stack. I think the idea was to match the behavior of MEAN and SDEV.

[Thomas Okken]

10C: No

[Gamo]

Example of the use of [∑+] for the HP-12C

Combination
01 ∑+ // Input Value to X and Y stack
02 RCL 2 // ∑x
03 X=0
04 GTO 12
05 ÷
06 STOx1 // n
07 1
08 STO-4 // ∑y
09 STO-2 // ∑x
10 RCL 4 // ∑y
11 GTO 02
12 RLC 1 // n

Remark: It simply performs Σ+

Gamo

[Thomas Klemm]

(02-07-2020 01:37 PM)Dave Britten Wrote:  Do any support STO Σ+ to store two values directly into the ΣX and ΣY registers?

The HP-48G supports both RCLΣ and STOΣ.
But here the entire dataset is recalled and stored.

I was pleasantly surprised by the following:

[LeftShift] ΣDAT → STOΣ
[RightShift] ΣDAT → RCLΣ

Both make perfect sense once you understand how those shift keys work with variables.