Thats a neat idea having the lookup tables, very very cool idea (: ----- Original Message ----- From: "Jonah Simpson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, October 31, 2004 12:10 PM Subject: Re: Witango-Talk: Distance Calculations - Sort on..., search on...
> Hey Daniel! > > What database are you using? I know MySQL can do the trigonometric > functions in a select statement and you could order your result from > the database... > > Doing trig functions is pretty gross efficiency wise. You might want > to store some of the functions that aren't going to change in your > location table. ie. Have columns for: > SIN(<@COLUMN 'Adressen.Geo_Breite'>) > COS(<@COLUMN 'Adressen.Geo_Breite'>) > in the same table that Adressen.Geo_Breite is stored in. As well, pre-calculate: > COS(@@User$Breite_1) and > SIN(@@User$Breite_1) to avoid doing this calculation 2500 times. > > You might want to play with that formula and optimize it. I'm not > super hot with my trig identites, but I'm sure you could put it into a > form that allows you to store as much information in the database as > possible. Then you would only have to do a couple of calculations in > your actual select statement. > > Interesting problem...let us know what route you eventually take. > > Cheers, > Jonah Simpson > [EMAIL PROTECTED] > > > On Sun, 31 Oct 2004 19:22:39 +0100, [EMAIL PROTECTED] > <[EMAIL PROTECTED]> wrote: > > > > Distance Calculation is no problem, that works. Here the formula: > > > > > > <@CALC EXPR="ACOS(SIN(@@User$Breite_1)*SIN(<@COLUMN 'Adressen.Geo_Breite'>) > > + COS(@@User$Breite_1)*COS(<@COLUMN 'Adressen.Geo_Breite'>)*COS(<@COLUMN > > 'Adressen.Geo_laenge'>-@@User$Laenge_1)) * 6378,388" Precision="1"> > > > > The problem what I have is: > > > > 1) To do a sort of the result (OK, I can do it in a array, but this need to > > much RAM [more as 2500 records, nearly 50x on one time]) > > > > 2) To do a search in a specified area like "show me all points near x > > miles(km). > > > > One way what make sense is to store the formula in the database, but > > - if i make a assign to a variable, then Witango store only the result. What > > I like to store is the formula-text: > > > > > > Second problem: I can't do a sort on the stored formula (Sort command: > > <@COLUMN 'Adressen.formel' Encoding="Metahtml">) > > > > Any Successions ? > > > > THX for help > > > > regards > > > > Daniel > > ________________________________________________________________________ > > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf > ________________________________________________________________________ > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf ________________________________________________________________________ TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf
