Computing atan2(x,y)  Hewlett Packard
This is a discussion on Computing atan2(x,y)  Hewlett Packard ; A recent post here (iirc) asked about computing atan2(x,y), the
inverse tan of y/x in the proper quadrant.
The current issue of The College Mathematics Journal has an article by
William Freed and Athanasios Tavouktsoglou with the following formula:
atan2(x,y) ...

Computing atan2(x,y)
A recent post here (iirc) asked about computing atan2(x,y), the
inverse tan of y/x in the proper quadrant.
The current issue of The College Mathematics Journal has an article by
William Freed and Athanasios Tavouktsoglou with the following formula:
atan2(x,y) = 2*atan(y/(x+sqrt(x^2+y^2)) except for x<0 and y=0;
pi for x<0 and y=0.
This might be of use.

Re: Computing atan2(x,y)
On Mar 5, 4:26 pm, mjc wrote:
> A recent post here (iirc) asked about computing atan2(x,y), the
> inverse tan of y/x in the proper quadrant.
>
> The current issue of The College Mathematics Journal has an article by
> William Freed and Athanasios Tavouktsoglou with the following formula:
>
> atan2(x,y) = 2*atan(y/(x+sqrt(x^2+y^2)) except for x<0 and y=0;
> pi for x<0 and y=0.
>
> This might be of use.
all HP calculators deal perfectly with this issue.
RTFM

Re: Computing atan2(x,y)
On Mar 5, 5:24*am, reth wrote:
> On Mar 5, 4:26 pm, mjc wrote:
>
> > A recent post here (iirc) asked about computing atan2(x,y), the
> > inverse tan of y/x in the proper quadrant.
>
> > The current issue of The College Mathematics Journal has an article by
> > William Freed and Athanasios Tavouktsoglou with the following formula:
>
> > atan2(x,y) = 2*atan(y/(x+sqrt(x^2+y^2)) except for x<0 and y=0;
> > * * * * * * * * * *pi for *x<0 and y=0.
>
> > This might be of use.
>
> all HP calculators deal perfectly with this issue.
> RTFM
I am not sure I understand you. With what issue do HP calculators
"deal perfectly?"
It can't be with an atan2 function. There is none in the catalog on my
HP 50g, and the 49 AUR is of no help.
It can't be with atan2(1, 0), per the formula given above, as it
results in "?".
Please explain.
= Secondary issue
I defined ATAN2 as described above, and attempted to construct
lim(ATAN2(X, 0), 0). CAS seems not to like userspecified functions.
Is this the case? How do people overcome this limitation? Recall the
variable and substitute 0 for Y?
 F

Re: Computing atan2(x,y)
The HP 33S manual suggests using rectangular to polar conversion for
arctan(y/x).

Re: Computing atan2(x,y)
"Curtis A. Jones" writes:
> The HP 33S manual suggests using rectangular to polar conversion for
> arctan(y/x).
On the HP48, you can enter x and y, and then
R\>C ARG
This will return an ATAN in degrees if in degree mode, or in radians if
in radian mode.
Scott

Scott Hemphill hemphill@alumni.caltech.edu
"This isn't flying. This is falling, with style."  Buzz Lightyear

Re: Computing atan2(x,y)
On Wed, 05 Mar 2008 12:51:33 0600, Scott Hemphill wrote:
> On the HP48, you can enter x and y, and then
>
> R\>C ARG
All HP48/49/50 have these same "user" commands.
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