HP 17bii+ solver equation question

[Don Shepherd]

Well, with all the talk about the 17bii+, I went out and bought one today. By the way, Les, it was $80 with my Office Depot Star Teacher discount! Anyhow, why can't the Change Sign (+/-) key be included in an equation?

[John Smitherman]

Don / Les, what are your impressions of the keys on your new 17bii+'s? What are their serial numbers?

Regards,

John

[Don Shepherd]

John, the keys seem fine, no skips or hard-to-press.

Serial # CNA62900787.

[Bruce Bergman]

Same here. I was a little concerned, what with the discussion, but so far the keys feel fine and haven't missed or doubled. The display is crystal clear -- very impressive.

I'm digging into the HP Solver on this thing which is -- quite happily to my surprise -- much more powerful than I thought. I'm going to have some fun with this one. :-)

thanks,
bruce

Oh, my S/N is CNA 63401403

Edited: 18 Feb 2007, 1:22 a.m.

[bill platt]

There is no use for the "change sign" command in an equation. You aren't "changing" anything when you are writing an equation. Rather, you are laying down a string of characters that are interpreted based on context. Therefore the minus sign and the plus sign are all you need--just as is the case when writing with a pencil.

For example:

2-3^2 is evaluated as 2 minus (3^2)

2--3^2 is evaluated as 2 plus (3^2)

2---3^2 is evaluated as 2 minus (3^2)

and

2+(-3^2) is also evaluated as 2 minus (3^2)

If you want to do:

(-3)^2

You have to do just that!

If you need to change anything, you have the cursor positioning aroows, and the <- delete key.

I hope that helps!

[Don Shepherd]

Yeah, thanks Bill. I'm making the transition between keystroke programming and equation "programming," and I'm learning the subtle differences between the two.