HP Forums
[WP 34s] Trouble finding root - (solved) - Printable Version

+- HP Forums (https://www.hpmuseum.org/forum)
+-- Forum: Not HP Calculators (/forum-7.html)
+--- Forum: Not quite HP Calculators - but related (/forum-8.html)
+--- Thread: [WP 34s] Trouble finding root - (solved) (/thread-4253.html)

[WP 34s] Trouble finding root - (solved) - Marcio - 06-29-2015 01:09 AM

Hello all,

I am having troubles finding the root of the following equation:

\[0.05=\frac{x\times coth(x) - 1}{10x\times coth(10x) - 1}\]

to which I created the following program:

Code:

LBL 01
#10
*
ENTER
TANH
/
1
-
x<>y
ENTER
TANH
/
1
-
x<>y
/
#005
#100
/
-
END

1
5
SLV 01

The 34s will complain there is a domain error.

Hope I am missing something.

Thanks

Marcio

EDIT: Found the error. Problem solved!

RE: [WP 34s] Trouble finding root - (solved) - Marcus von Cube - 06-29-2015 07:37 AM

(06-29-2015 01:09 AM)Marcio Wrote:  EDIT: Found the error. Problem solved!

It would be interesting for others to know what went wrong and how you fixed it.

RE: [WP 34s] Trouble finding root - (solved) - RMollov - 06-29-2015 11:06 AM

(06-29-2015 01:09 AM)Marcio Wrote:  Hello all,

I am having troubles finding the root of the following equation:

\[0.05=\frac{x\times coth(x) - 1}{10x\times coth(10x) - 1}\]

to which I created the following program:

Code:

LBL 01
#10
*
ENTER
TANH
/
1
-
x<>y
ENTER
TANH
/
1
-
x<>y
/
#005
#100
/
-
END

1
5
SLV 01

The 34s will complain there is a domain error.

Hope I am missing something.

Thanks

Marcio

EDIT: Found the error. Problem solved!

You could save a few steps:
Code:
LBL 01
XEQ 00
X<>Y
SDL 001
ENTER
XEQ 00
/
#005
SDR002
-
RTN
LBL 00
TANH
/
1
-
END


RE: [WP 34s] Trouble finding root - (solved) - Marcio - 06-29-2015 11:13 AM

(06-29-2015 07:37 AM)Marcus von Cube Wrote:  
(06-29-2015 01:09 AM)Marcio Wrote:  EDIT: Found the error. Problem solved!

It would be interesting for others to know what went wrong and how you fixed it.

The 34s complained because the first guess I entered was zero.

RE: [WP 34s] Trouble finding root - (solved) - Marcio - 06-29-2015 11:23 AM

(06-29-2015 11:06 AM)RMollov Wrote:  You could save a few steps:
Code:
LBL 01
XEQ 00
X<>Y
SDL 001
ENTER
XEQ 00
/
#005
SDR002
-
RTN
LBL 00
TANH
/
1
-
END

Yes, much shorter. Thanks.

RE: [WP 34s] Trouble finding root - (solved) - Dieter - 06-29-2015 06:59 PM

(06-29-2015 11:23 AM)Marcio Wrote:  Yes, much shorter. Thanks.

Both shorter and faster, using the some special 34s features:

Code:
LBL 01
TANH
/
DEC X
X<> Y
SDL 001
ENTER
TANH
/
DEC X
/
#005
SDR 002
-
END

1 [ENTER] 5 [SLV] 01
=> 1,64561382716

Dieter

RE: [WP 34s] Trouble finding root - (solved) - Marcio - 06-29-2015 07:20 PM

Indeed. Faster than the solver of the 35s too.

RE: [WP 34s] Trouble finding root - (solved) - Marcio - 08-05-2015 01:40 AM

Code:

LBL 1
1
0
*
ENTER
TANH
/
1
-
x<>y
ENTER
TANH
/
1
-
x<>y
/
0
.
0
5
/
-
END

Gentlemen,

I have been trying to solve this equation for X using the 15C but it is not working.

Anyway, the code above will make the 15C output 0.0389, which is not correct. Could you identify what I am missing here?

Please note that there has been no attempt to optimize the given code.

Very much appreciated.

Marcio

RE: [WP 34s] Trouble finding root - (solved) - Didier Lachieze - 08-05-2015 03:48 AM

Marcio Wrote:  Could you identify what I am missing here?

Just remove the last "/", before the "-".

RE: [WP 34s] Trouble finding root - (solved) - Marcio - 08-05-2015 04:03 AM

(08-05-2015 03:48 AM)Didier Lachieze Wrote:  
Marcio Wrote:  Could you identify what I am missing here?

Just remove the last "/", before the "-".

Oh yes, I forgot to remove that extra /. Thanks.