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Clear Stack (CLST, CLSTK) and LastX
03-16-2015, 07:03 AM
Post: #21
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 06:28 AM)Thomas Klemm Wrote:  23 apples @ $0.43
47 eggs @ $0.17

I see this as something near $10 + $7.99, my misspent youth playing too many card games helped here since 3*17 is rather related to a deck of cards Smile A few seconds' further contemplation gives me the $17.88 answer but it isn't close to instantaneous. On a calculator I would have used the ENTER key for this one.

If you went to three or four digit numbers, I'd reach for a calculator sooner of course. An arithmetic savant I'm not and the many amazing records of mental arithmetic are in no danger of being beaten by myself.


You could calculate this as: 529 SQRT 43 * 289 SQRT 47 * + which is a bit convoluted but only because I didn't bother with square numbers much beyond thirty.


And finally, the big question: what are you using 23 apples and 47 eggs for????? Smile


Pauli
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03-16-2015, 07:27 AM (This post was last modified: 03-16-2015 07:27 AM by toml_12953.)
Post: #22
RE: Clear Stack (CLST, CLSTK) and LastX
[quote='Thomas Klemm' pid='30756' dateline='1426483232']
Quote:I wonder how you calculate 7*9+3*13 with your method.

Cheers
Thomas

This works on the 35s:

7 STO A 9 * 3 STO A 13 * +

Tom L

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03-16-2015, 07:32 AM
Post: #23
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:03 AM)Paul Dale Wrote:  And finally, the big question: what are you using 23 apples and 47 eggs for????? Smile

A big apple-pie to celebrate \(\pi\)-day of course.
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03-16-2015, 07:35 AM
Post: #24
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:27 AM)toml_12953 Wrote:  This works on the 35s:

7 STO A 9 * 3 STO A 13 * +

Tom L

Not sure whether you're familiar with Marcus' method.
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03-16-2015, 07:56 AM
Post: #25
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:27 AM)toml_12953 Wrote:  This works on the 35s:

7 STO A 9 * 3 STO A 13 * +
More Marcus-like:
Code:
CLR_STK
7
+
9
*
x<>y
3
+
13
*
+
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03-16-2015, 07:59 AM (This post was last modified: 03-16-2015 09:21 AM by Paul Dale.)
Post: #26
RE: Clear Stack (CLST, CLSTK) and LastX
So we should have a top level NOP key to replace ENTER???
Seems rather pointless.

Pauli
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03-16-2015, 08:12 AM
Post: #27
RE: Clear Stack (CLST, CLSTK) and LastX
Hi all,
This discution is very interesting but i thing that "Lastx" is very usefull and helpfull for correcting mistakes or store value "indirectly". Since my first hp 25 in 1976 to hp 50g (and Prime, of course), i have hundreds routines which have almost all "Lastx" inside.

Hp 50g have "Lastarg" wich is a bit different, with obligation using "drop" to convert to "Lastx".

I'm happy that WP 34s has the "Rcl L" exactly similar "Lastx".

Gérard.

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03-16-2015, 09:03 AM
Post: #28
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:59 AM)Paul Dale Wrote:  So we should behave a top level NOP key to replace ENTER???
Seems rather pointless.

Pauli

Of course it is.
But someone felt compelled to explain how to use RPN...

Greetings,
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03-16-2015, 09:15 AM
Post: #29
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:59 AM)Paul Dale Wrote:  So we should behave a top level NOP key to replace ENTER???
Seems rather pointless.

Not if you have a dead Enter key Tongue
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03-16-2015, 09:29 AM
Post: #30
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 07:56 AM)Thomas Radtke Wrote:  More Marcus-like:
Code:
CLR_STK
7
+
9
*
x<>y
3
+
13
*
+

It's easy to find a sequence where you need more key-strokes than the obvious:

7
ENTER
9
*
3
ENTER
13
*
+


Don't ever try to calculate something more advanced like:

\(\frac{(7\times9 + 3\times13)(4\times17+6\times7)}{9\times11+13\times5}\)


Cheers
Thomas
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03-16-2015, 09:40 AM
Post: #31
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 09:29 AM)Thomas Klemm Wrote:  It's easy to find a sequence where you need more key-strokes than the obvious:
Yes, but looking at the various methods can be fun. I don't think even Marcus takes this too serious ;-).
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03-16-2015, 09:48 AM (This post was last modified: 03-16-2015 09:56 AM by Paul Dale.)
Post: #32
RE: Clear Stack (CLST, CLSTK) and LastX
\( \forall x \geq 0: x \equiv (\sqrt{x})^2 \)

So using three extra keystrokes per number (√, shift & x2), we're home and hosed.


- Pauli
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03-16-2015, 09:52 AM
Post: #33
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 09:48 AM)Paul Dale Wrote:  \( \forall x: x \equiv (\sqrt{x})^2 \)
Wouldn't this be more accurate:

\( \forall x: x \equiv \sqrt{x^2} \)

(serious question, I don't know the answer)
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03-16-2015, 09:58 AM
Post: #34
RE: Clear Stack (CLST, CLSTK) and LastX
Bummer, left out the ≥0 which I meant to include.
Fixed now.

The problem with the √ is that it is two valued -- both positive and negative.


- Pauli
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03-16-2015, 10:13 AM (This post was last modified: 03-16-2015 10:17 AM by Thomas Klemm.)
Post: #35
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 09:29 AM)Thomas Klemm Wrote:  \(\frac{(7\times9 + 3\times13)(4\times17+6\times7)}{9\times11+13\times5}\)

(03-16-2015 09:40 AM)Thomas Radtke Wrote:  Yes, but looking at the various methods can be fun.

On the HP-48 I don't need an [ENTER] key:

7 9×
3 13×
+
4 17×
6 7×
+
*
9 11×
13 5×
+
÷

Cheers
Thomas
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03-16-2015, 10:16 AM
Post: #36
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 09:48 AM)Paul Dale Wrote:  So using three extra keystrokes per number (√, shift & x2), we're home and hosed.

You could use [x<>y] twice instead.

Cheers
Thomas
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03-16-2015, 10:30 AM
Post: #37
RE: Clear Stack (CLST, CLSTK) and LastX
(03-16-2015 10:13 AM)Thomas Klemm Wrote:  On the HP-48 I don't need an [ENTER] key:
[font=Courier]
7 9× [...]
Never used this and didn't even knew that works outside of a program. Nice.
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