Re: [sqlite] function named geopolyCosine is a misnomer
On 12/1/18, John G wrote: > Is there any documentation on the > geopoly extension? > https://www.sqlite.org/search?s=d&q=geopoly https://www.sqlite.org/geopoly.html -- D. Richard Hipp d...@sqlite.org ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] function named geopolyCosine is a misnomer
If I missed i tin earlier posts, sorry. Is there any documentation on the geopoly extension? With possible uses or examples? John On Thu, 29 Nov 2018 at 14:39, Richard Hipp wrote: > On 11/29/18, Thomas Kurz wrote: > > Could it be that the one angle is north-based, the other one east-based? > > Ha Ha. No, Graham is right. I started out writing a Cosine function, > then I switched it over to be a Sine function but failed to change the > name. A rename has now been committed to trunk, is in the latest > "prerelease snapshot", and will appear in the next official release > (which will also be the first official release that includes the new > capability). > > -- > D. Richard Hipp > d...@sqlite.org > ___ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] function named geopolyCosine is a misnomer
On 11/29/18, Thomas Kurz wrote: > Could it be that the one angle is north-based, the other one east-based? Ha Ha. No, Graham is right. I started out writing a Cosine function, then I switched it over to be a Sine function but failed to change the name. A rename has now been committed to trunk, is in the latest "prerelease snapshot", and will appear in the next official release (which will also be the first official release that includes the new capability). -- D. Richard Hipp d...@sqlite.org ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] function named geopolyCosine is a misnomer
Could it be that the one angle is north-based, the other one east-based? - Original Message - From: Graham Hardman To: SQLite mailing list Sent: Thursday, November 29, 2018, 12:46:05 Subject: [sqlite] function named geopolyCosine is a misnomer Hi, I was very interested in the numerical approximation used in the function named geopolyCosine and after a bit of on-line research decided to test it's accuracy myself. What I discovered was that the function in fact returns the sin value rather than the cosine value. This is quickly noticed by checking the return value when r = 0. The value returned is 0 rather than the expected 1.0 The function is only employed by the geopoly_regular function which I found does actually return the expected shape (taking into account the approximation being used). On checking the geopoly_regular program code I saw that the coordinate calculation formulae cancel out the incorrect value returned from geopolyCosine by essentially reversing the normal understanding of sin and cosine. I hope it is understood that I do not wish to offend. I would, in fact appreciate a link to the site where this approximation was discovered. regards, Graham ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] function named geopolyCosine is a misnomer
Hi, I was very interested in the numerical approximation used in the function named geopolyCosine and after a bit of on-line research decided to test it's accuracy myself. What I discovered was that the function in fact returns the sin value rather than the cosine value. This is quickly noticed by checking the return value when r = 0. The value returned is 0 rather than the expected 1.0 The function is only employed by the geopoly_regular function which I found does actually return the expected shape (taking into account the approximation being used). On checking the geopoly_regular program code I saw that the coordinate calculation formulae cancel out the incorrect value returned from geopolyCosine by essentially reversing the normal understanding of sin and cosine. I hope it is understood that I do not wish to offend. I would, in fact appreciate a link to the site where this approximation was discovered. regards, Graham ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
