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HP50g ABS value Graph
08-12-2021, 04:09 AM
Post: #1
HP50g ABS value Graph
I’m surely doing something wrong, but I can’t get my 50g to correctly graph this simple f(x)=lx2-1l function. It graphs it as if the absolute value wasn’t there. I’ve tried everything I know, but nothing changes. My HP48GX graphs the right result…
What am I doing wrong? Could that be caused by a flag I set or unset?? Is it a bug?
I don’t understand.

Thanks for your help.

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08-12-2021, 05:36 AM
Post: #2
RE: HP50g ABS value Graph
You wrote:
f(x)=lx2-1l
Do you mean x*2 or is x2 a variable?
I put in in the equation writer:
Abs(x-1) and it worked perfect.
Abs(x*2-1) works as well.
Abs(x2-1) has no effect at all.
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08-12-2021, 05:39 AM
Post: #3
RE: HP50g ABS value Graph
(08-12-2021 04:09 AM)Neve Wrote:  I’m surely doing something wrong, but I can’t get my 50g to correctly graph this simple f(x)=lx2-1l function. It graphs it as if the absolute value wasn’t there. I’ve tried everything I know, but nothing changes. My HP48GX graphs the right result…
What am I doing wrong? Could that be caused by a flag I set or unset?? Is it a bug?
I don’t understand.

Thanks for your help.
That's a quite common problem. Make sure you have selected CAS setting "Rigorous" checked.
If that option is non-checked, calculator simplify |2x-1| to 2x-1. So it draws wrong graph.

CAS setting Rigorous : Don't simplify |x| to X?

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08-12-2021, 05:45 AM
Post: #4
RE: HP50g ABS value Graph
(08-12-2021 05:36 AM)rawi Wrote:  You wrote:
f(x)=lx2-1l
Do you mean x*2 or is x2 a variable?
I put in in the equation writer:
Abs(x-1) and it worked perfect.
Abs(x*2-1) works as well.
Abs(x2-1) has no effect at all.

I mean f(x)=absolute value of x square -1

What result do you get? What I get is just the result of x square - 1, the absolute value is not taken into account.

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08-12-2021, 05:47 AM
Post: #5
RE: HP50g ABS value Graph
(08-12-2021 05:39 AM)BINUBALL Wrote:  
(08-12-2021 04:09 AM)Neve Wrote:  I’m surely doing something wrong, but I can’t get my 50g to correctly graph this simple f(x)=lx2-1l function. It graphs it as if the absolute value wasn’t there. I’ve tried everything I know, but nothing changes. My HP48GX graphs the right result…
What am I doing wrong? Could that be caused by a flag I set or unset?? Is it a bug?
I don’t understand.

Thanks for your help.
That's a quite common problem. Make sure you have selected CAS setting "Rigorous" checked.
If that option is non-checked, calculator simplify |2x-1| to 2x-1. So it draws wrong graph.

CAS setting Rigorous : Don't simplify |x| to X?

THANK YOU!!! That was exactly the problem.

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08-12-2021, 05:48 AM (This post was last modified: 08-12-2021 05:49 AM by 3298.)
Post: #6
RE: HP50g ABS value Graph
It's flag -119, "Rigorous" mode. Clear it and things should work again.

The calculator will simplify about-to-be-graphed equations for performance reasons, and it uses the generic simplification routine also accessible to the user via commands, some parts of which are controlled by flags. This particular one also appears in the MODE -> CAS settings form (last row, left edge of the screen; a few others only appear in the flag browser), where its hint is "Don't simplify |X| to X?".

Edit: oh man, too late again...
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08-12-2021, 06:30 AM
Post: #7
RE: HP50g ABS value Graph
(08-12-2021 05:48 AM)3298 Wrote:  It's flag -119, "Rigorous" mode. Clear it and things should work again.

The calculator will simplify about-to-be-graphed equations for performance reasons, and it uses the generic simplification routine also accessible to the user via commands, some parts of which are controlled by flags. This particular one also appears in the MODE -> CAS settings form (last row, left edge of the screen; a few others only appear in the flag browser), where its hint is "Don't simplify |X| to X?".

Edit: oh man, too late again...

Don’t worry. Thank you for having taken the time to answer.

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