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Re: Re: First function debug help

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106693] Re: [mg106665] Re: [mg106627] First function debug help
  • From: Herman Kuun <oomkoos1 at gmail.com>
  • Date: Thu, 21 Jan 2010 04:53:19 -0500 (EST)
  • References: <201001191013.FAA29027@smc.vnet.net>

Yep. I looked-up the jDM algorithme and check what it is all about. Thx.

On Wed, Jan 20, 2010 at 8:47 PM, DrMajorBob <btreat1 at austin.rr.com> wrote:

> Actually, BOTH functions fail, and for the same reason, nothing to do with
> h.
>
> Since m_ is used twice in each function signature, once for months and
> again for minutes, the functions only work when months = seconds. A couple
> of examples:
>
> julianDayModified[y_, m_, d_, h_, m_,
>  s_] := (b =
>   2 - IntegerPart[y/100] + IntegerPart[IntegerPart[y/100]/4];
>  f = d + (h/24) + (m/(24*60)) + (s/(24*3600));
>  jd = IntegerPart[(365.25*(y + 4716))] +
>    IntegerPart[(30.6001*(m + 1))] + d + b - 1524.5;
>  mjd = jd - 2400000.5;
>  mjd)
> julianDayModified[2010, 1, 1, 12, 0, 0]
>
> julianDayModified[2010, 1, 1, 12, 0, 0]
>
> (no evaluation, because no match)
>
> julianDayModified[2010, 1, 1, 12, 1, 0]
>
> 55195.
>
> Instead, try something like:
>
> Clear@julianDayModified
> julianDayModified[y_, month_, d_, h_, minute_,
>  s_] := (b =
>   2 - IntegerPart[y/100] + IntegerPart[IntegerPart[y/100]/4];
>  f = d + (h/24) + (minute/(24*60)) + (s/(24*3600));
>  jd = IntegerPart[(365.25*(y + 4716))] +
>    IntegerPart[(30.6001*(month + 1))] + d + b - 1524.5;
>  mjd = jd - 2400000.5;
>  mjd)
>
> Bobby
>
> On Wed, 20 Jan 2010 05:50:48 -0600, Herman Kuun <oomkoos1 at gmail.com>
> wrote:
>
>  The hour input 'h_' is not used in the defined function.
>>
>> Substitute
>>   d = d + ((m * 60 )/ ( 24 * 60 )) + ((s * 3600)/(24 * 3600));
>> with
>>  f = d + (h/24) + (m/(24*60)) + (s/(24*3600));
>>
>> Also try make it a habit to start your own variable and function
>> definitions
>> in lower case. Mathematica uses upper case exclusively. Save you lots of
>> frustration in the future.
>>
>> This will calculate corectly:
>>
>> ------------------------------------------------------------------------------------------------------------
>>
>> julianDayModified[y_, m_, d_, h_, m_,   s_] := (
>>
>>  b = 2 - IntegerPart[y/100] + IntegerPart[IntegerPart[y/100]/4];
>>
>>  f = d + (h/24) + (m/(24*60)) + (s/(24*3600));
>>
>>  jd = IntegerPart[(365.25*(y + 4716))] +
>>    IntegerPart[(30.6001*(m + 1))] + d + b - 1524.5;
>>
>>  mjd = jd - 2400000.5;
>>
>>  mjd
>>
>>  )
>>
>> julianDayModified[2010, 1, 1, 12, 0, 0]
>>
>> 55164.
>>
>>
>> ---------------------------------------------------------------------------------------------------------------
>> Best
>> Herman
>>
>> On Tue, Jan 19, 2010 at 12:13 PM, Canopus56 <canopus56 at yahoo.com> wrote:
>>
>>  I took a stab at writing my first function - converting a system
>>> formatted
>>> list date into a Modified Julian Day.  The function appears to be written
>>> properly, but does not return anything.
>>>
>>> Any help in debugging it would be appreciated.
>>>
>>> Ideally, I would like to send a date-time list in the form {y,m,d,h,m,s}
>>> to
>>> the function and have the Julian Day returned.
>>>
>>> Thanks for your help - Kurt
>>>
>>> (* This function computes the Modified Julian Day from a \
>>> system formatted date. Domain is restricted to Greogorian dates. \
>>> Source: Meeus. 1998. Chap. 7. Astronomical Alogrithms. *)
>>> (* fractionalize the day value *)
>>>
>>> JulianDayModified[y_, m_, d_, h_, m_, s_] := (
>>>  B = 2 - IntegerPart[y/100] + IntegerPart[IntegerPart[y/100]/4];
>>>  d = d + ((m * 60 )/ ( 24 * 60 )) + ((s * 3600)/(24 * 3600));
>>>  JD = IntegerPart[(365.25*(y + 4716))] +
>>>  IntegerPart[(30.6001*(m + 1 ))] + d + b - 1524.5;
>>>  MJD = JD - 2400000.5;
>>>  MJD
>>>  )
>>>
>>> JulianDayModified[2010, 1, 1, 12, 0, 0]
>>>
>>> Returns the string "
>>> JulianDayModified[2010, 1, 1, 12, 0, 0]"
>>>
>>> and not the computed date
>>>
>>> Also tried it this way with the Module statement with no change in the
>>> result:
>>>
>>> JulianDayModified[y_, m_, d_, h_, m_, s_] := Module[{B, JD, MJD},
>>>  B = 2 - IntegerPart[y/100] + IntegerPart[IntegerPart[y/100]/4];
>>>  d = d + ((m*60)/(24*60)) + ((s*3600)/(24*3600));
>>>  JD = IntegerPart[(365.25*(y + 4716))] +
>>>  IntegerPart[(30.6001*(m + 1))] + d + b - 1524.5;
>>>  MJD = JD - 2400000.5;
>>>  MJD
>>>  ]
>>>
>>>
>>
>>
>>
>
> --
> DrMajorBob at yahoo.com
>



-- 
Best
Herman
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