Velocity Reviews > What's wrong with my arc tangens calculation?

# What's wrong with my arc tangens calculation?

xliiv
Guest
Posts: n/a

 09-14-2012
I do some math with python:

import math as m
m.degrees(m.atan(2))
>>> 63.43494882292201

but when i lookup tg in a paper table (last decade math book) i've got these values:

tg(63'10'') = 1.9768
tg(63'20'') = 1.9912
tg(63'30'') = 2.0057

For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)

what's wrong?

Chris Angelico
Guest
Posts: n/a

 09-14-2012
On Fri, Sep 14, 2012 at 8:49 PM, xliiv <(E-Mail Removed)> wrote:
> I do some math with python:
>
> import math as m
> m.degrees(m.atan(2))
>>>> 63.43494882292201

>
> but when i lookup tg in a paper table (last decade math book) i've got these values:
>
> tg(63'10'') = 1.9768
> tg(63'20'') = 1.9912
> tg(63'30'') = 2.0057
>
> For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)

..43494882292201 degrees = 26.0969294 arcminutes

So I would say that your table and Python are in agreement. Do you
know what the notation 63'30" means?

ChrisA

Laszlo Nagy
Guest
Posts: n/a

 09-14-2012

> but when i lookup tg in a paper table (last decade math book) i've got these values:
>
> tg(63'10'') = 1.9768
> tg(63'20'') = 1.9912
> tg(63'30'') = 2.0057
>
> For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)
>
> what's wrong?
>

63° 30" is 63.5°. So nothing is wrong. (You know, 1° = 60 arc second!)

xliiv
Guest
Posts: n/a

 09-14-2012
On Friday, September 14, 2012 12:55:06 PM UTC+2, Laszlo Nagy wrote:
> > but when i lookup tg in a paper table (last decade math book) i've got these values:

>
> >

>
> > tg(63'10'') = 1.9768

>
> > tg(63'20'') = 1.9912

>
> > tg(63'30'') = 2.0057

>
> >

>
> > For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)

>
> >

>
> > what's wrong?

>
> >

>
> 63ï¿½ 30" is 63.5ï¿½. So nothing is wrong. (You know, 1ï¿½ = 60 arc second!)

So the wrong part is me
The python's 63.43494882292201 is degrees (according to function math.degrees)
but book's value is in minutes. Clearified Thanks, all.

xliiv
Guest
Posts: n/a

 09-14-2012
On Friday, September 14, 2012 12:55:06 PM UTC+2, Laszlo Nagy wrote:
> > but when i lookup tg in a paper table (last decade math book) i've got these values:

>
> >

>
> > tg(63'10'') = 1.9768

>
> > tg(63'20'') = 1.9912

>
> > tg(63'30'') = 2.0057

>
> >

>
> > For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)

>
> >

>
> > what's wrong?

>
> >

>
> 63ï¿½ 30" is 63.5ï¿½. So nothing is wrong. (You know, 1ï¿½ = 60 arc second!)

So the wrong part is me
The python's 63.43494882292201 is degrees (according to function math.degrees)
but book's value is in minutes. Clearified Thanks, all.

Mark Lawrence
Guest
Posts: n/a

 09-14-2012
On 14/09/2012 11:54, Chris Angelico wrote:
> On Fri, Sep 14, 2012 at 8:49 PM, xliiv <(E-Mail Removed)> wrote:
>> I do some math with python:
>>
>> import math as m
>> m.degrees(m.atan(2))
>>>>> 63.43494882292201

>>
>> but when i lookup tg in a paper table (last decade math book) i've got these values:
>>
>> tg(63'10'') = 1.9768
>> tg(63'20'') = 1.9912
>> tg(63'30'') = 2.0057
>>
>> For me python should return something more like 63'2x'' than 63'4x''(becasue 63'30'' is higher than 2.0)

>
> .43494882292201 degrees = 26.0969294 arcminutes
>
> So I would say that your table and Python are in agreement. Do you
> know what the notation 63'30" means?
>
> ChrisA
>

Somebody or something has a length, height or width of 63 feet 30 inches?

--
Cheers.

Mark Lawrence.

Chris Angelico
Guest
Posts: n/a

 09-14-2012
On Fri, Sep 14, 2012 at 11:13 PM, Mark Lawrence <(E-Mail Removed)> wrote:
> Somebody or something has a length, height or width of 63 feet 30 inches?

Sounds like the height of a building with a barometer. The thirty
inches, of course, being the height of the barometer.

ChrisA
(big, big barometer)