Re: [fpc-pascal] convert "epoch" to UTC

[Sven Barth]

Am 16.01.2012 04:10 schrieb "waldo kitty" :
>
>
> i'm needing to convert a "UTC epoch" date to a "standard time string"...
by that, i mean that i want to get something like "2011-01-13 22:24:04" out
of the "epoch" number 12013.9338171...
>
> the above "epoch" number is (supposedly) built like this...
>
> 12 == 2012
> 013 == 13th day of the year
> .9338171 * 24 == 22.4116104 hours
> .4114104 * 60 == 24.696624 minutes
>
> and here's where it breaks on me because
>
> .696624 * 60 == 41.79744 seconds and that doesn't match the above time
string showing 04 seconds... that time string was built from this "epoch"
number (by another program) and i assume that it followed this published
formula for this format (which is for satellite TLEs)...
>
> so, my question is this... is there an existing FPC routine that will
convert this (or a part of this) properly or do i need to play with
something to get it right? it is obvious that this is not a "unix epoch"...
i'm not sure how "normal" julian date epochs are represented...
>
> i've looked through the docs on freepascal.org but none of them show an
number with which to compare... there's no links pointing to a definition
or example of a julian date or unix date or any such...

I don't know whether your format is really a Julian or Unix time (for
Julian it looks too low), but can take a look at unit "DateUtils" of which
the documentation is here:
http://www.freepascal.org/docs-html/rtl/dateutils/index-5.html
Especially you can try JulianToDateTime and UnixToDateTime. Both return a
TDateTime which you can convert to a string using FormatDateTime (
http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostring.html ) or
DateTimeToStr (
http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostr.html).

Regards,
Sven
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

[fpc-pascal] Re: convert "epoch" to UTC

[Lukasz Sokol]

On 16/01/2012 03:09, waldo kitty wrote:
> 
> i'm needing to convert a "UTC epoch" date to a "standard time
> string"... by that, i mean that i want to get something like
> "2011-01-13 22:24:04" out of the "epoch" number 12013.9338171...
> 
> the above "epoch" number is (supposedly) built like this...
> 
> 12 == 2012 013 == 13th day of the year .9338171 * 24 == 22.4116104
> hours .4114104 * 60 == 24.696624 minutes
> 
> and here's where it breaks on me because
> 
> .696624 * 60 == 41.79744 seconds and that doesn't match the above
> time string showing 04 seconds... that time string was built from
> this "epoch" number (by another program) and i assume that it
> followed this published formula for this format (which is for
> satellite TLEs)...
> 
> so, my question is this... is there an existing FPC routine that will
> convert this (or a part of this) properly or do i need to play with
> something to get it right? it is obvious that this is not a "unix
> epoch"... i'm not sure how "normal" julian date epochs are
> represented...
> 
> i've looked through the docs on freepascal.org but none of them show
> an number with which to compare... there's no links pointing to a
> definition or example of a julian date or unix date or any such...
> 
> help! please :/
> 

See what Sven Barth said, for DateUtils
but also as for seconds mismatch, may it be due to leap seconds ?
http://en.wikipedia.org/wiki/Leap_second

which actually shows that current TAI - UTC = 34 seconds
(TAI = International Atomic Time) this actually is it: 41 - 34 = 7
(it's not 4 unfortunately but still close ?) 

(I guess satellite position is rather relative to TAI than UTC?)

(Or some float calculation bug like 
http://en.wikipedia.org/wiki/Pentium_FDIV_bug
 (or some float-to-string representation problem))
Lukasz


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] Postscriptcanvas

[David Copeland]

This would be for printing.


-Original Message-
From: Felipe Monteiro de Carvalho 
Reply-to: FPC-Pascal users discussions 
To: FPC-Pascal users discussions 
Subject: Re: [fpc-pascal] Postscriptcanvas
Date: Sun, 15 Jan 2012 13:11:13 -0200

On Fri, Jan 13, 2012 at 3:31 PM, David Copeland
 wrote:
> Is it possible to use the PostScriptCanvas unit in a non-gui program?

For drawing or for printing?


-- 
David Copeland
JSI Data Systems Limited
613-727-9353.


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

[fpc-pascal] convert "epoch" to UTC (waldo kitty)

[edgar jordan]

12 == 2012
013 == 13th day of the year
.9338171 * 24 == 22.4116104 hours
.4114104 * 60 == 24.696624 minutes


The decimal portion of hours doesn't match the one multiplied by 60. I just
thought it's the one causing the discrepancy.
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] Re: convert "epoch" to UTC

[Jeff Wormsley]

I went here:

http://www.satellite-calculations.com/TLETracker/SatTracker.htm

It had the TLE for Galaxy 15 as follows:

GALAXY 15
1 28884U 05041A   10133.62484064  .0085  0-0  1-3 0  8291
2 28884 000.1391 078.0756 0002640 331.8937 274.1784 01.00285599 16790

And did these calculations (using Calc on Ubuntu)

10133.62484064 - Thu May 13 2010 10:59:46 GMT-0400 (EDT) = Thu May 13 
2010 14:59:46 GMT


10 - 2010
133 - 133rd day (assume that's Thu May 13 - didn't check)

0.62484064 * 24 = 14.99617536
0.99617536 * 60 =  59.7705216
0.7705216 * 60 = 46.231296

Seems ok to me...

Replacing there time stamp in that web site with your example gives the 
same answer you got.  Either that web site is wrong, too, or your 
example was wrong.


Jeff.
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 06:22, Sven Barth wrote:

Am 16.01.2012 04:10 schrieb "waldo kitty" 
 >
 >
 > i'm needing to convert a "UTC epoch" date to a "standard time string"... by
 > that, i mean that i want to get something like "2011-01-13 22:24:04" out of
 > the "epoch" number 12013.9338171...


TYPO ALERT! that should be .93338171... with the additional '3' in there, the 
final value for the seconds is 4... long day, tired eyes and dirty glasses :/


[TRIM]

 > so, my question is this... is there an existing FPC routine that will convert
 > this (or a part of this) properly or do i need to play with something to get
 > it right? it is obvious that this is not a "unix epoch"... i'm not sure how
 > "normal" julian date epochs are represented...
 >
 > i've looked through the docs on freepascal.org  but
 > none of them show an number with which to compare... there's no links 
pointing
 > to a definition or example of a julian date or unix date or any such...

I don't know whether your format is really a Julian or Unix time (for Julian it
looks too low),


it is actually one of the "julian" ones... it is the "julian day of year" 
format... at least that's what i believe it is called...



but can take a look at unit "DateUtils" of which the
documentation is here:
http://www.freepascal.org/docs-html/rtl/dateutils/index-5.html


yes, i had been all in there... that's where i was expecting to see an example 
that actually contained a number that would be converted to a date so that one 
might work out the math manually if desired... without a number, i had nothing 
to compare what i have with to see if it was even close...



Especially you can try JulianToDateTime and UnixToDateTime. Both return a
TDateTime which you can convert to a string using FormatDateTime
( http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostring.html ) or
DateTimeToStr ( 
http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostr.html ).


i think i might be able to do something with the JulianToDateTime once i get the 
base year portion converted to a true julian... i spotted some C# code while 
doing a bit of research earlier (see below)... it appears to convert the year to 
a julian year and then add the decimal day portion... this should then be a 
proper julian date which i should be able to handle ;)


[ WARNING: C# code follows ]
double getJulianDay_Year(int year)
{
double dYear = year - 1;
double A = Math.Floor(dYear / 100);
double B = 2 - A + Math.Floor(A / 4);
//The use of 30.601 is to correct for floating point rounding 
problems

double dResult = Math.Floor(365.25 * dYear) + 1721422.9 + B;
return dResult;
}

double getJulianDay_SatEpoch(int year, double dSatelliteEpoch)
{
//Tidy up the year and put it into the correct century
year = year % 100;
if (year < 57) year += 2000;
else year += 1900;

double dResult = getJulianDay_Year(year);
dResult += dSatelliteEpoch;

return dResult;
}
[ end of C# code ]

looks like it should be easy to convert to pascal, too ;) just gotta find out 
what that "floor" routine does ;)


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC (waldo kitty)

[waldo kitty]

On 1/16/2012 09:44, edgar jordan wrote:

12 == 2012
013 == 13th day of the year
.9338171 * 24 == 22.4116104 hours


i typoed the above... it should be

.93338171 * 24 == 22.40116104 hours


.4114104 * 60 == 24.696624 minutes


so this becomes

.40116104 * 60 == 24.0696624 minutes

which then leads to

.0696624 * 60 == 4.179744 seconds



The decimal portion of hours doesn't match the one multiplied by 60. I just
thought it's the one causing the discrepancy.


ahhh... it took me a minute to find that errant '4' in there :lol: yeah, that 
could cause the problem but in this case, i dropped a '3' much earlier :/


so, i'm on the right track... just gotta use the right numbers... now to find 
the right formula ;)


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] Re: convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 10:00, Jeff Wormsley wrote:

I went here:

http://www.satellite-calculations.com/TLETracker/SatTracker.htm


funny thing, that! when i woke up this morning and went researching, that was 
the first site that uncle google showed me, too :lol:



It had the TLE for Galaxy 15 as follows:

GALAXY 15
1 28884U 05041A 10133.62484064 .0085 0-0 1-3 0 8291
2 28884 000.1391 078.0756 0002640 331.8937 274.1784 01.00285599 16790


i pasted in my ISS TLE and got the result i had been looking for in my example 
string... that told me that /I/ had goofed something... turns out that i had 
dropped a '3' in the decimal julian day portion of the number... there should 
have been three 3s together... it made all the difference, too ;)


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[Sven Barth]

On 16.01.2012 17:57, waldo kitty wrote:

Especially you can try JulianToDateTime and UnixToDateTime. Both return a
TDateTime which you can convert to a string using FormatDateTime
(
http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostring.html
) or
DateTimeToStr (
http://www.freepascal.org/docs-html/rtl/sysutils/datetimetostr.html ).


i think i might be able to do something with the JulianToDateTime once i
get the base year portion converted to a true julian... i spotted some
C# code while doing a bit of research earlier (see below)... it appears
to convert the year to a julian year and then add the decimal day
portion... this should then be a proper julian date which i should be
able to handle ;)

[ WARNING: C# code follows ]
double getJulianDay_Year(int year)
{
double dYear = year - 1;
double A = Math.Floor(dYear / 100);
double B = 2 - A + Math.Floor(A / 4);
//The use of 30.601 is to correct for floating point
rounding problems
double dResult = Math.Floor(365.25 * dYear) + 1721422.9 + B;
return dResult;
}

double getJulianDay_SatEpoch(int year, double dSatelliteEpoch)
{
//Tidy up the year and put it into the correct century
year = year % 100;
if (year < 57) year += 2000;
else year += 1900;

double dResult = getJulianDay_Year(year);
dResult += dSatelliteEpoch;

return dResult;
}
[ end of C# code ]

looks like it should be easy to convert to pascal, too ;) just gotta
find out what that "floor" routine does ;)


Well... I would say the same as FPC's "floor" routine ( 
http://www.freepascal.org/docs-html/rtl/math/floor.html ) does ;)


A hint for converting C# code: it might help to google for (in this 
case) "Math.Floor .net" which will often result in a MSDN link like this 
one: http://msdn.microsoft.com/en-us/library/e0b5f0xb.aspx


Regards,
Sven
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[Ralf A. Quint]

At 09:40 AM 1/16/2012, Sven Barth wrote:

Well... I would say the same as FPC's "floor" routine ( 
http://www.freepascal.org/docs-html/rtl/math/floor.html ) does ;)

Well... someone might want to check the example for that function ;)

Ralf 


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[Mark Morgan Lloyd]

waldo kitty wrote:

i think i might be able to do something with the JulianToDateTime once i 
get the base year portion converted to a true julian... i spotted some 
C# code while doing a bit of research earlier (see below)... it appears 
to convert the year to a julian year and then add the decimal day 
portion... this should then be a proper julian date which i should be 
able to handle ;)


Don't know whether any of this will help

If this is any use...

FUNCTION CalcJD(year, month, day: INTEGER): DOUBLE;

//***/
//* Name:CalcJD */
//* Type:Function   */
//* Purpose: Julian day from calendar day   */
//* Arguments:  */
//*   year : 4 digit year   */
//*   month: January = 1*/
//*   day  : 1 - 31 */
//* Return value:   */
//*   The Julian day corresponding to the date  */
//* Note:   */
//*   Number is returned for start of day.  Fractional days should be   */
//*   added later.  */
//***/

VAR A, B: INTEGER;
JD: DOUBLE;

BEGIN
  IF month <= 2 THEN BEGIN
year -= 1;
month += 12
  END;
  A:= Floor(year / 100);
  B:= 2 - A + Floor(A / 4);
  JD:= Floor(365.25 * (year + 4716)) + Floor(30.6001 * (month + 1)) + 
day + B - 1524.5;

  RESULT:= JD
END { CalcJD } ;

That was derived from some calculations published by NOAA, it's actually 
sunrise/sunset times and I transcribed it from Javascript a few months 
ago and which appeared to test OK.


Also

FUNCTION jTime(t: Int64): DOUBLE;

// jtime - convert internal date and time to astronomical Julian
// time (i.e. Julian date plus day fraction)

BEGIN
  RESULT:= t;
  RESULT:= (RESULT / 86400.0) + 2440587.5   // (seconds /(seconds 
per day)) + julian date of epoch

END { jTime } ;


FUNCTION jDayToSecs(jday: DOUBLE): Int64;

// jdaytosecs - convert Julian date to a UNIX epoch

BEGIN
  RESULT:= Round((jday - 2440587.5) * 86400)   // (juliandate - jdate 
of unix epoch)*(seconds per julian day)

END { jDayToSecs } ;


PROCEDURE jYear(td: DOUBLE; VAR yy, mm: Int64; VAR dd: DOUBLE);

// jyear - convert Julian date to year, month, day, which are
// returned via integer pointers to integers

VAR z, a, alpha, b, c, d, e: Int64;
f: DOUBLE;

BEGIN
  td:= td + 0.5;   // astronomical to civil
  z:= Floor(td);
  f:= td - z;
  IF z < 2299161 THEN
a:= z
  ELSE BEGIN
alpha:= Floor((z - 1867216.25) / 36524.25);
a:= z + 1 + alpha - Floor(alpha / 4)
  END;
  b:= a + 1524;
  c:= Floor((b - 122.1) / 365.25);
  d:= Floor(365.25 * c);
  e:= Floor((b - d) / 30.6001);

(* Note here: both MoonPhase.pm and moontool.c lose fractional days at 
this *)
(* point since dd is declared as an integer; Perl programmers might not 
in  *)
(* fact notice this due to loose type handling. I think this is a bug 
since it  *)
(* prevents using non-GMT time ranges. MarkMLl. 
*)


  dd:= b - d - Floor(30.6001 * e) + f;
  IF e < 14 THEN
mm:= e - 1
  ELSE
mm:= e - 13;
  IF mm > 2 THEN
yy:= c - 4716
  ELSE
mm:= c - 4715
END { jYear } ;


PROCEDURE jYear(td: DOUBLE; VAR yy, mm, dd: Int64);

// jyear - convert Julian date to year, month, day, which are
// returned via integer pointers to integers

(* This is equivalent to the original jYear() which loses fractional 
days.  *)
(* MarkMLl. 
*)


VAR y, m: Int64;
d: DOUBLE;

BEGIN
  jYear(td, y, m, d);
  yy:= y;
  mm:= m;
  dd:= Trunc(d)
END { jYear } ;

which was transcribed from Perl (originally written in C) Moon phase 
calculations and again I believe tests OK.


--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 12:40, Sven Barth wrote:

On 16.01.2012 17:57, waldo kitty wrote:

[TRIM]

looks like it should be easy to convert to pascal, too ;) just gotta
find out what that "floor" routine does ;)


Well... I would say the same as FPC's "floor" routine (
http://www.freepascal.org/docs-html/rtl/math/floor.html ) does ;)


hehe, exactly... and it was easy to convert, too...


function getJulianDay_Year(year:integer) : double;
var
  dYear,
  a,b,
  dResult : double;
begin
  dYear := year - 1;
  A := Floor(dYear / 100);
  B := 2 - A + Math.Floor(A / 4);
  //The use of 30.601 is to correct for floating point rounding 
problems

  dResult := Floor(365.25 * dYear) + 1721422.9 + B;
  getJulianDay_Year := dResult;
end;

function getJulianDay_SatEpoch(year:integer; dSatelliteEpoch:double) : double;
var
  dResult : double;
begin
  //Tidy up the year and put it into the correct century
  year := year mod 100;
  if (year < 57) then
year := year + 2000
  else
year := year + 1900;

  dResult := getJulianDay_Year(year);
  dResult := dResult + dSatelliteEpoch;

  getJulianDay_SatEpoch := dResult;
end;


with this TLE epoch number, 12013.93338171, ya feed it like so...

var
  JEpoch : double;
  DT : TDateTime;

[...]
JEpoch := getJulianDay_SatEpoch(12,013.93338171);
[...]
  if TryJulianDateToDateTime(JEpoch,DT) then
writeln(FormatDateTime(' MM DD hh:mm:ss',DT));


the above /should/ return 2012 01 14 22:24:04... i'm getting the right dates 
back but all of the times are 00:00:00 :(


do JulianDateToDateTime and TryJulianDateToDateTime not do anything with hours, 
minutes, seconds and milliseconds??


i'd give TryModifiedJulianDateToDateTime a try but the docs state that just 
trying to use that routine raises an exception... is it going to handle the 
hors, minutes, seconds, and milliseconds when it gets done or is it for some 
other julian date format??


[ aside: where/how does one report documentation errors? PadLeft says to see 
also PadLeft instead of PadRight ;) ]

___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 12:54, Ralf A. Quint wrote:

At 09:40 AM 1/16/2012, Sven Barth wrote:


Well... I would say the same as FPC's "floor" routine (
http://www.freepascal.org/docs-html/rtl/math/floor.html ) does ;)

Well... someone might want to check the example for that function ;)


+1

especially since the example is for ceil ;)

___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 13:38, Mark Morgan Lloyd wrote:

waldo kitty wrote:


i think i might be able to do something with the JulianToDateTime once i get
the base year portion converted to a true julian... i spotted some C# code
while doing a bit of research earlier (see below)... it appears to convert the
year to a julian year and then add the decimal day portion... this should then
be a proper julian date which i should be able to handle ;)


Don't know whether any of this will help


that actually looks very similar to some of my old TP/BP 6/7 time libraries that 
i created because there was not much available out there when i needed it... the 
one part that hit me the most was that the fractional days stuff is lost and 
that's one part of what i'm looking for... however, i think i do have a method 
to pull it out... maybe i can make it generic enough for use elsewhere where 
decimal julian dates are used... i'm still coding it in my head and will be 
putting fingers to keyboard in just a bit to actually put it into operation ;)


thanks for the input!

___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[Sven Barth]

On 16.01.2012 20:06, waldo kitty wrote:

with this TLE epoch number, 12013.93338171, ya feed it like so...

var
JEpoch : double;
DT : TDateTime;

[...]
JEpoch := getJulianDay_SatEpoch(12,013.93338171);
[...]
if TryJulianDateToDateTime(JEpoch,DT) then
writeln(FormatDateTime(' MM DD hh:mm:ss',DT));


the above /should/ return 2012 01 14 22:24:04... i'm getting the right
dates back but all of the times are 00:00:00 :(

do JulianDateToDateTime and TryJulianDateToDateTime not do anything with
hours, minutes, seconds and milliseconds??


A quick look at the code reveiled that it doesn't handle it. But at 
least that one should be the same as the one TDateTime uses, so you 
might try the following (which you can then pack into a function yourself):


var
  JEpoch: Double;
  DT: TDateTime;
begin
  JEpoch := getJulianDay_SatEpoch(12,013.9338171);
  if TryJulianDateToDateTime(JEpoch, DT) then begin
DT := DT + Frac(JEpoch); // the time part should be the one after 
the comma in both Julian and DateTime models
Writeln(FormatDateTime(' MM DD hh:nn:ss', DT)); // you need to 
use "nn" for minutes as listed here: 
http://www.freepascal.org/docs-html/rtl/sysutils/formatchars.html

  end;
end;



i'd give TryModifiedJulianDateToDateTime a try but the docs state that
just trying to use that routine raises an exception... is it going to
handle the hors, minutes, seconds, and milliseconds when it gets done or
is it for some other julian date format??


The three "Modified Julian Date" functions are implemented as follows, 
so there should be no exception if you use the 
TryModifiedJulianDateToDateTime function (this seems to be another 
documentation error then):


Function DateTimeToModifiedJulianDate(const AValue: TDateTime): Double;
begin
  result := DateTimeToJulianDate(AValue) - 240.5;
end;


Function ModifiedJulianDateToDateTime(const AValue: Double): TDateTime;
begin
  result := JulianDateToDateTime(AValue + 240.5);
end;


Function TryModifiedJulianDateToDateTime(const AValue: Double; out 
ADateTime: TDateTime): Boolean;

begin
  Result:=TryJulianDateToDateTime(AValue + 240.5, ADateTime);
end;



[ aside: where/how does one report documentation errors? PadLeft says to
see also PadLeft instead of PadRight ;) ]


You can report all documentation errors at http://bugs.freepascal.org as 
well. Just select as Category "Documentation".


Regards,
Sven
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[Mark Morgan Lloyd]

waldo kitty wrote:


Don't know whether any of this will help


that actually looks very similar to some of my old TP/BP 6/7 time 
libraries that i created because there was not much available out there 
when i needed it... the one part that hit me the most was that the 
fractional days stuff is lost and that's one part of what i'm looking 
for... however, i think i do have a method to pull it out... maybe i can 
make it generic enough for use elsewhere where decimal julian dates are 
used... i'm still coding it in my head and will be putting fingers to 
keyboard in just a bit to actually put it into operation ;)


The ultimate reference for almost all this stuff usually turns out to be 
one of Jean Meeus's books.


--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

[fpc-pascal] tthread.waitfor with timeout

[Jorge Aldo G. de F. Junior]

hi !

while working on my pascal actor model concurrency framework i hit a
problem with the way tthread is currently implemented.

i need to quit all actors (threads) before closing the main
application. this is done by waitfor/free each actor until none is
left in the pool of locally running actors.

but sometimes an actor hangs, and waitfor will literally waitfor forever...

is there a way to do the equivalent of waifor but with some kind of timeout ?

thanks in advance,

J. Aldo
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] tthread.waitfor with timeout

[Jonas Maebe]

On 16 Jan 2012, at 22:25, Jorge Aldo G. de F. Junior wrote:

> is there a way to do the equivalent of waifor but with some kind of timeout ?

No. And at least the Unix pthreads library does not offer such an API, so it 
can't be added without some kind of emulation either (adding an extra event per 
thread or so to wait on -- but every thread already consumes quite a few extra 
such resources, and they should be kept to a minimum).


Jonas___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

[fpc-pascal] Would someone be willing to build the skeleton of a simple application for me?

[hdv . jadev]

Hi,

I am not really sure if this type of message is appreciated on this list or 
not. I tried looking it up on the Lazarus-site, but didn't find anything on it. 
My apologies if you think I shouldn't have sent this.

Quite a few years ago I was a reasonably decent Delphi programmer. But after 
my move to Linux-only systems more than a decade ago I stopped using Pascal (I 
did try Kylix for a short while). The last couple of years I've been very busy 
building my company, so during those years I've had no time for development at 
all.

However I am beginning to feel the itch again and would like to pick up where 
I left. On top of that I'd also like to give some students of mine a simple 
dictionary application for company specific vocabulary. So I thought to combine 
both and build it myself. It seemed like a good way to get myself reacquainted 
with Pascal and in this case Lazarus. I still think it will be, but I am 
getting soacked up in work again and there's a need for the application before 
March.

So here's my request: would someone be willing to get me started by building 
the basics when given the specs? Basically it concerns a sqlite database with 
just three tables (each with four or less fields) and the interface to query 
and manipulate them. All in all probably not more than 3 forms will be needed. 
More detailed specs are available.

I think it will not take more than one or two days for an experienced 
programmer and it doesn't have to be a full product. Just something that does 
what is needed and enough to get me up and running in a short time. Polishing 
the thing later on will be a good learning project for me.

I am willing to pay for this, as long as the fee is reasonable and the 
developer doesn't have any objections to have his code made available under an 
OSS license.

Anyone interested, please contact me directly and off-list.

Sincerely,

HdV
___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal

Re: [fpc-pascal] convert "epoch" to UTC

[waldo kitty]

On 1/16/2012 14:49, Sven Barth wrote:

On 16.01.2012 20:06, waldo kitty wrote:

with this TLE epoch number, 12013.93338171, ya feed it like so...

var
JEpoch : double;
DT : TDateTime;

[...]
JEpoch := getJulianDay_SatEpoch(12,013.93338171);
[...]
if TryJulianDateToDateTime(JEpoch,DT) then
writeln(FormatDateTime(' MM DD hh:mm:ss',DT));


the above /should/ return 2012 01 14 22:24:04... i'm getting the right
dates back but all of the times are 00:00:00 :(

do JulianDateToDateTime and TryJulianDateToDateTime not do anything with
hours, minutes, seconds and milliseconds??


A quick look at the code reveiled that it doesn't handle it.


i kinda figured that... however, here's a nice li'l :TripleFacePalm: for ya...

i tried to describe the format of the TLE Epoch number in an earlier post but i 
guess i pretty much failed... at least insofar as what the actual format is... 
here's what i posted previously...


[quote]
>> i'm needing to convert a "UTC epoch" date to a "standard time string"... by
>> that, i mean that i want to get something like "2011-01-13 22:24:04" out of
>> the "epoch" number 12013.9338171...
>>
>> the above "epoch" number is (supposedly) built like this...
>>
>> 12 == 2012
>> 013 == 13th day of the year
>> .9338171 * 24 == 22.4116104 hours
>> .4114104 * 60 == 24.696624 minutes
[/quote]

yes, that's the one where i dropped a '3' in the fractional part ;)

anyway, the format is like this...

*_TLE Epoch Format_*

eg: 12013.93338171

1. there are always 5 digits to the left of the decimal. the first two digits
   are the year of the epoch.

   if year<57 then year:=year+2000 else year:=year+1900

   in the above, 12 is the year which is 2012.

2. the next three digits (up to the decimal point) are the "day number of the
   year" of the TLE Epoch record.

   in the above, 013 is the day number of the year. feed this plus the year
   to a julian date routine to find the julian date number. in this example,
   we're looking for the julian date number for the 13th day of 2012.

3. the digits from the decimal point to the end are the fractional part of
   the day. these are /not/ in julian date or julian day format.

   in the above, .93338171 is the fractional part of the day. the time portion
   of the formula goes like this.

   fooo := frac(12013.93338171)
   rslt := fooo * 24// 22.40116104
   hour := trunc(rslt)  // 22
   fooo := frac(rslt)   // .40116104
   rslt := fooo * 60// 24.0696624
   mins := trunc(rslt)  // 24
   fooo := frac(rslt)   // .0696624
   rslt := fooo * 60// 4.179744
   secs := trunc(rslt)  // 4
   fooo := frac(rslt)   // .179744
   rslt := fooo * 1000  // the more zeros, the more precision
   msec := trunc(rslt)  // 179

4. convert the julian date number from #2 to TDateTime. fill in the TDateTime
   time fields from #3. now EncodeDateTime and you'll have the proper numbers
   in a TDateTime record.

so what i ran into, besides the julian date routines not doing the time, but i 
was also sending the entire decimal number, without the year digits, to the 
julian date routine and that was just flat wrong since the fractional side 
wasn't a julian date fraction! ::TripleFacePalm::


so there's three pieces of data stored in that one "TLE Epoch" number and each 
has to be broken out and treated differently... now my answers finally agree 
with the programs i've been attempting to verify them against... i just couldn't 
see the forest for the trees and couldn't see the trees for all the leaves on'em 
:LOL:


___
fpc-pascal maillist  -  fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal