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From: <noreply@so...>  20021022 07:15:53

Bugs item #626721, was opened at 20021022 03:15 You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
From: SourceForge.net <noreply@so...>  20060701 02:54:59

Bugs item #626721, was opened at 20021022 01:15 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&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: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
From: SourceForge.net <noreply@so...>  20060909 14:54:28

Bugs item #626721, was opened at 20021022 01:15 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&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: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
From: SourceForge.net <noreply@so...>  20061109 04:13:04

Bugs item #626721, was opened at 20021022 03:15 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&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: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  >Comment By: Raymond Toy (rtoy) Date: 20061108 23:13 Message: Logged In: YES user_id=28849 Isn't this formula also wrong? For y=1, x=1, the formula becomes %i*log((1%i)/sqrt(2)). But log is the principal log so we still get %pi/4. I think it would be better to make atan2 be in the range (%pi,%pi].  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
From: SourceForge.net <noreply@so...>  20061109 04:26:30

Bugs item #626721, was opened at 20021022 03:15 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&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: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  >Comment By: Raymond Toy (rtoy) Date: 20061108 23:26 Message: Logged In: YES user_id=28849 Oops. I think the formula was intended to be %i*log((x+%i*y)/sqrt(x^2+y^2)). That produces the correct values. At least factor(rectform(<formula>)) produces atan2(y/r,x/r) with r = sqrt(x^2+y^2). It would be nice if atan2 simplified out the denominator to leave only atan2(y,x).  Comment By: Raymond Toy (rtoy) Date: 20061108 23:13 Message: Logged In: YES user_id=28849 Isn't this formula also wrong? For y=1, x=1, the formula becomes %i*log((1%i)/sqrt(2)). But log is the principal log so we still get %pi/4. I think it would be better to make atan2 be in the range (%pi,%pi].  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
From: SourceForge.net <noreply@so...>  20061109 14:00:30

Bugs item #626721, was opened at 20021022 03:15 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&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: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: logarc of atan2 wrong Initial Comment: res : logarc(atan2(y,x))$ rectform(res),y=1,x=1; => %pi/4 BUT atan2(1,1) => 3*%pi/4 The fix is to change the formula in $logarc and in simpatan2. Currently, logarc(atan2(y,x)) => logarc(atan (y/x)), which gives incorrect results as above. This formula should be replaced by %i*log((y+%i*x)/sqrt(x^2+y^2))  >Comment By: Raymond Toy (rtoy) Date: 20061109 09:00 Message: Logged In: YES user_id=28849 Fixed as suggested, with slight correction.  Comment By: Raymond Toy (rtoy) Date: 20061108 23:26 Message: Logged In: YES user_id=28849 Oops. I think the formula was intended to be %i*log((x+%i*y)/sqrt(x^2+y^2)). That produces the correct values. At least factor(rectform(<formula>)) produces atan2(y/r,x/r) with r = sqrt(x^2+y^2). It would be nice if atan2 simplified out the denominator to leave only atan2(y,x).  Comment By: Raymond Toy (rtoy) Date: 20061108 23:13 Message: Logged In: YES user_id=28849 Isn't this formula also wrong? For y=1, x=1, the formula becomes %i*log((1%i)/sqrt(2)). But log is the principal log so we still get %pi/4. I think it would be better to make atan2 be in the range (%pi,%pi].  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626721&group_id=4933 
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