From: SourceForge.net <noreply@so...>  20030524 22:27:46

Bugs item #742909, was opened at 20030524 18:27 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 4 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: trigrat(sin(x/2)) makes a mess Initial Comment: trigrat(sin(x/2)) => (%I*(SIN(x/2)*SIN(x)+COS(x/2)*COS(x)COS(x/2)) COS(x/2)*SIN(x)+SIN(x/2)*COS(x)SIN(x/2))/(2*SIN(x/2) ^2+2*COS(x/2)^2) Although this is correct, I doubt that this is what trigrat is supposed to do. After all, it has not eliminated sin (x/2); the result contains sin(x/2), but also contains sin^2+cos^2, so it doesn't seem "more linear" in any sense. Also, it is not a canonical form: trigrat(ev(sin (x/2),halfangles)) gives something else (even messier). Note also that sin(2*x) does not expand in trigrat.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 
From: SourceForge.net <noreply@so...>  20060707 05:16:22

Bugs item #742909, was opened at 20030524 16:27 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. >Category: Lisp Core Group: None Status: Open Resolution: None Priority: 4 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: trigrat(sin(x/2)) makes a mess Initial Comment: trigrat(sin(x/2)) => (%I*(SIN(x/2)*SIN(x)+COS(x/2)*COS(x)COS(x/2)) COS(x/2)*SIN(x)+SIN(x/2)*COS(x)SIN(x/2))/(2*SIN(x/2) ^2+2*COS(x/2)^2) Although this is correct, I doubt that this is what trigrat is supposed to do. After all, it has not eliminated sin (x/2); the result contains sin(x/2), but also contains sin^2+cos^2, so it doesn't seem "more linear" in any sense. Also, it is not a canonical form: trigrat(ev(sin (x/2),halfangles)) gives something else (even messier). Note also that sin(2*x) does not expand in trigrat.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 
From: SourceForge.net <noreply@so...>  20060827 00:22:06

Bugs item #742909, was opened at 20030524 16:27 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. >Category: Lisp Core  Trigonometry Group: None Status: Open Resolution: None Priority: 4 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: trigrat(sin(x/2)) makes a mess Initial Comment: trigrat(sin(x/2)) => (%I*(SIN(x/2)*SIN(x)+COS(x/2)*COS(x)COS(x/2)) COS(x/2)*SIN(x)+SIN(x/2)*COS(x)SIN(x/2))/(2*SIN(x/2) ^2+2*COS(x/2)^2) Although this is correct, I doubt that this is what trigrat is supposed to do. After all, it has not eliminated sin (x/2); the result contains sin(x/2), but also contains sin^2+cos^2, so it doesn't seem "more linear" in any sense. Also, it is not a canonical form: trigrat(ev(sin (x/2),halfangles)) gives something else (even messier). Note also that sin(2*x) does not expand in trigrat.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 
From: SourceForge.net <noreply@so...>  20100511 00:08:52

Bugs item #742909, was opened at 20030525 00:27 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core  Trigonometry Group: None >Status: Closed >Resolution: Fixed Priority: 4 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: trigrat(sin(x/2)) makes a mess Initial Comment: trigrat(sin(x/2)) => (%I*(SIN(x/2)*SIN(x)+COS(x/2)*COS(x)COS(x/2)) COS(x/2)*SIN(x)+SIN(x/2)*COS(x)SIN(x/2))/(2*SIN(x/2) ^2+2*COS(x/2)^2) Although this is correct, I doubt that this is what trigrat is supposed to do. After all, it has not eliminated sin (x/2); the result contains sin(x/2), but also contains sin^2+cos^2, so it doesn't seem "more linear" in any sense. Also, it is not a canonical form: trigrat(ev(sin (x/2),halfangles)) gives something else (even messier). Note also that sin(2*x) does not expand in trigrat.  >Comment By: Dieter Kaiser (crategus) Date: 20100511 02:08 Message: Fixed in trigrat.lisp revision 1.9. Closing this bug report as fixed. Dieter Kaiser  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=742909&group_id=4933 