How do I input the 'dx' into the HP 34s to calculate f'x when I wish a different increment than the default of .1?

You know that the default dx is 0,1 so you probably have read the respective information regarding the f'(x) command:

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ATTENTION: f’(x) will look for a user routine labeled 'delta x', returning a fixed step size dx in X.

If that routine is not defined, dx = 0.1 is set for default (arbitrary, but it had to be specified).

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[f] [LBL] [ENTER]     display shows  LBL '

[f] [^] (EXIT key with the yellow arrow)  switches to lower case

[g] [D]  enters a (now lower case) greek delta

 X  (on the "." key)  enters a (still lower case) x

[ENTER] completes the command (and cancels lower case mode).

001 LBL'delta x'   / "delta" = lower case delta character

002 1

003 SDR 3

004 RTN

Dieter

Richard, Dieter has already answered your question. I'd just like to add that the name of the device does not start with an 'H' but with a 'W'. ;-)

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So you simply have to provide a routine labelled with a lower case (!) greek delta and a lower case x.

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Not quite. The calculator looks for all possible different case versions of delta and x in this order:

1. [delta]x
   
2. [delta]X
   
3. [DELTA]x
   
4. [DELTA]X
   

- Pauli

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Richard, Dieter has already answered your question. I'd just like to add that the name of the device does not start with an 'H' but with a 'W'. ;-)

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"give Caesar, what Caesar's (to Caesar belong)"...I don't know how to translate it in english, but correct remark, Marcus

Matthew 22:21 Give unto Caeser what is Caeser's, and to God what is God's.

I think it could be "Give credit where credit is due" or "Give the devil his due". Idiomatic expressions are sneaky...

:-)

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I don't know how to translate it in english

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As late as when I was 17 my mother made me attend Sunday School every Sunday, so I still remember this:

http://en.wikipedia.org/wiki/Render_unto_Caesar...

It's a good thing 'W' is also an upside down 'M' so the whole Trinity is there :-)

Edited: 3 Mar 2013, 5:36 p.m.

Fine - but in this case this should also be documented in the manual. The current version says two lowercase characters are mandatory.

Finally, also the search order should be reversed since an uppercase [DELTA] X is the easiest way to enter a valid label, so it should be found as fast as possible. :-)

Dieter

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It's a good thing 'W' is also an upside down 'M' so the whole Trinity is there :-)

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d;-)

There has been a lot of work put in by others as well.

- Pauli

... please read the acknowledments in 'Welcome'.

d:-)

Or just execute the WHO command. :-)

The most prominent contributions are by:

Neil who wrote the assembler which is an integral part of the build system,

Pascal who is the 'portability guy' in the team, responsible for the cross platform emulators (stay tuned!) but also for the stop watch,

Harald who has added USB to the system,

Katie who laid the foundation of the printing hardware.

A lot of input came from other regulars of this friendly and collaborative place.

We have to thank all of them!

Eric who has laboured manufacturing the keyboard overlay.

Sorry, my omission...

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Eric who has laboured manufacturing the keyboard overlay.

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Which gives the WP 34S a pro look, thus befitting your efforts and others. BTW, mine has just been applied a brand-new overlay. Eric, thank you very much!