# What's wrong with my arc tangens calculation?

Discussion in 'Python' started by xliiv, Sep 14, 2012.

1. ### xliivGuest

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?

xliiv, Sep 14, 2012

2. ### Chris AngelicoGuest

On Fri, Sep 14, 2012 at 8:49 PM, xliiv <> 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

Chris Angelico, Sep 14, 2012

3. ### Laszlo NagyGuest

> 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!)

Laszlo Nagy, Sep 14, 2012
4. ### xliivGuest

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, Sep 14, 2012
5. ### xliivGuest

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, Sep 14, 2012
6. ### Mark LawrenceGuest

On 14/09/2012 11:54, Chris Angelico wrote:
> On Fri, Sep 14, 2012 at 8:49 PM, xliiv <> 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.

Mark Lawrence, Sep 14, 2012
7. ### Chris AngelicoGuest

On Fri, Sep 14, 2012 at 11:13 PM, Mark Lawrence <> 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)

Chris Angelico, Sep 14, 2012