Precedence Rule with Function App
04-22-2015, 07:55 PM (This post was last modified: 04-22-2015 07:56 PM by John Colvin.)
Post: #1
 John Colvin Member Posts: 173 Joined: Dec 2013
Precedence Rule with Function App
When plotting the function x^2/2 - 1/2 in the function app, the plot appears as
(x/2)^2 - 1/2 which is incorrect according to precedence rules. This error does
not occur on the HP50G. I can get the correct plot if I enter 1/2(x)^2-1/2.
Is there a reason that powers have the same or less
precedence than division?
04-22-2015, 08:09 PM
Post: #2
 Han Senior Member Posts: 1,882 Joined: Dec 2013
RE: Precedence Rule with Function App
(04-22-2015 07:55 PM)John Colvin Wrote:  When plotting the function x^2/2 - 1/2 in the function app, the plot appears as
(x/2)^2 - 1/2 which is incorrect according to precedence rules. This error does
not occur on the HP50G. I can get the correct plot if I enter 1/2(x)^2-1/2.
Is there a reason that powers have the same or less
precedence than division?

Did you press the right arrow one too many times prior to the [x^y] button (in textbook mode)? Otherwise, I am unable to replicate your observations whether in algebraic or textbook entry mode.

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04-22-2015, 08:12 PM
Post: #3
 John Colvin Member Posts: 173 Joined: Dec 2013
RE: Precedence Rule with Function App
After deleting and reentering the function x^2/2-1/2, I got the correct plot, so I have no idea what is happening. I entered the function exactly the same way when I
reentered it. Has anyone else encountered this issue?
04-22-2015, 08:19 PM
Post: #4
 John Colvin Member Posts: 173 Joined: Dec 2013
RE: Precedence Rule with Function App
(04-22-2015 08:09 PM)Han Wrote:
(04-22-2015 07:55 PM)John Colvin Wrote:  When plotting the function x^2/2 - 1/2 in the function app, the plot appears as
(x/2)^2 - 1/2 which is incorrect according to precedence rules. This error does
not occur on the HP50G. I can get the correct plot if I enter 1/2(x)^2-1/2.
Is there a reason that powers have the same or less
precedence than division?

Did you press the right arrow one too many times prior to the [x^y] button (in textbook mode)? Otherwise, I am unable to replicate your observations whether in algebraic or textbook entry mode.

No, I didn't, however I was in RPN mode. I doubt if you will be able to reproduce this.
Sorry I posted this since it seems to be a one time occurrence.
04-22-2015, 10:00 PM
Post: #5
 Han Senior Member Posts: 1,882 Joined: Dec 2013
RE: Precedence Rule with Function App
(04-22-2015 08:19 PM)John Colvin Wrote:
(04-22-2015 08:09 PM)Han Wrote:  Did you press the right arrow one too many times prior to the [x^y] button (in textbook mode)? Otherwise, I am unable to replicate your observations whether in algebraic or textbook entry mode.

No, I didn't, however I was in RPN mode. I doubt if you will be able to reproduce this.
Sorry I posted this since it seems to be a one time occurrence.

In textbook mode, typing X / 2 and then pressing the right arrow (twice?) makes it so that the [x^y] key applies to the entire expression currently displayed. That's one way to reproduce what you got.

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