HP-50G Equation Editing Logic

[Matt Agajanian]

Hello all.

Perhaps you could help me understand the 50G editing methodology. In the Equation Writer example from pages User's Manual pages 2-7 and 2-8, why would the expression need to be entirely highlighted in order to add the '+1/3' expression to the right. Wouldn't it be a better editing philosophy to just position the cursor to the right of that '5/(5+2(...' expression?

Yes, yes, since the MacOS/Windows GUI tactic is that typing over a selected/highlighted block of text replaces, why wouldn't the 50G's equation editing follow that philosophy? Like I said, wouldn't it be easier to just position the cursor left or right instead of highlighting a subexpression to append to it?

So, perhaps you could help me understand the 50G's editing methodology?

Edited: 20 Apr 2012, 2:07 p.m.

[bill platt]

"...MacOS/Windows...why wouldn't the 50G's equation editing follow that philosophy?"

How about because they ^#ck.

The equation editor went through some interesting evolutions. The original one which is part of the 48G is essentially an incomplete tool but gave the framework to build a great tool. With MetaKernel, that tool became reality for the 48GX and for the 49 and all later.

The basic problem is making sure you achieve the precedence you intend.

Note that the equation editor is not a text editor paradigm, nor is it a raster paradigm. It is very specifically a equation editor--nothing less, but nothing more, either. It seems to me that this design simplifies the problem of syntax error which would result from parsing a more general text or raster expression.

[Matt Agajanian]

Okay then. As yes, as this is equation editing and not text editing, this is an equation editing philosophy which has stepped leaps forward from the editing traits from which the 48SX/GX began. So, with that in mind, what are the editing rules, characteristics, techniques now for the 50G series that I need to modify/reframe from the older 48 series editing methods?

Edited: 20 Apr 2012, 3:55 p.m.

[Gilles Carpentier]

"Yes, yes, since the MacOS/Windows GUI tactic is that typing over a selected/highlighted block of text replaces, why wouldn't the 50G's equation editing follow that philosophy?"

In fact, that is what the calc do ... if you enter number or variable.But if you enter a function, the function apply to the selected part of the equation. (the same way you can choose italic or bold in a GUI) Ex :

12 + 25 -> 3 give 3

12 + 25 -> SIN give SIN(12+25)

12 + 25 -> * 3 give (12+25).3

12 + 25 -> SHIFT CLEAR delete the selection

For the example of the book I do :

5 / 5 + 2 () 5 + PI y^x 2 -> / 2 Rshift&Up + 1 / 3

Note that * is not necessery before ()

It's not obvious to explain the logic but it's very 'natural' with some experience... In fact i think that the best way is to try ;)

For example :

- you can useLShift&Left to exchange 2 parts of a selected part of equation
- You can use UNDO wich is sometime very practical
- You can edit )a part of an equation ( very practicle for removing a square root or trig function for example

If the example of the english book is the same as the french one, note there is a much simplier way to drop the '1/3' in the equation with the square root :

RShift&Up Down Right <= (<= for the delete key)

Edited: 20 Apr 2012, 9:18 p.m.

[Matt Agajanian]

Hello there.

Giles, thanks for clarifying the methodology with your distinction of the differences involved (value replacement versus function append):

In fact, that is what the calc do ... if you enter number or variable.But if you enter a function, the function apply to the selected part of the equation. (the same way you can choose italic or bold in a GUI)

That's the point I needed--the differentiation between a variable or function being typed over the selected sub-expression. Now I have a better understanding of how the Equation Writer operates. Thanks.

Edited: 20 Apr 2012, 11:23 p.m.