## [Maxima-bugs] [ maxima-Bugs-823084 ] IS often doesn't work

 [Maxima-bugs] [ maxima-Bugs-823084 ] IS often doesn't work From: SourceForge.net - 2003-10-17 12:54:31 ```Bugs item #823084, was opened at 2003-10-14 00:37 Message generated for change (Comment added) made by diemer You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 Category: Tests Group: None Status: Closed Resolution: Invalid Priority: 5 Submitted By: Jonas Diemer (diemer) Assigned to: Nobody/Anonymous (nobody) Summary: IS often doesn't work Initial Comment: Hi! The IS function is used to evaluate if an expression is true, correct? It doesn't seem to like equations that are not factored out: 2*(x-(y+x))=2*x-2*(y+x); should be true, right? IS sais, it wasn't. Jonas PS: I am not an expert in CAS. If I reported complete bullshit, I would be happy about a short explanation why. thanks in advance. ---------------------------------------------------------------------- >Comment By: Jonas Diemer (diemer) Date: 2003-10-17 14:54 Message: Logged In: YES user_id=154672 I see. Maybe somthing about testing equality etc. could go in the Primer or somewhere else... Regards ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2003-10-17 08:18 Message: Logged In: YES user_id=588346 In Maxima, is(...=...) tests for *syntactic* equality: the two expressions have the same structure. To test for *semantic* equality, use equal. In your example, is(equal(2*(x-(y+x)),2*x-2*(y+x)) returns true as you'd expect. That said, in many cases is/equal cannot determine the correct result, even if other parts of Maxima can -- e.g. is (equal(sin(x)^2+cos(x)^2,1)). I agree that this is confusing, but this is the intended behavior. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 ```

 [Maxima-bugs] [ maxima-Bugs-823084 ] IS often doesn't work From: SourceForge.net - 2003-10-13 22:37:31 ```Bugs item #823084, was opened at 2003-10-14 00:37 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=823084&group_id=4933 Category: Tests Group: None Status: Open Resolution: None Priority: 5 Submitted By: Jonas Diemer (diemer) Assigned to: Nobody/Anonymous (nobody) Summary: IS often doesn't work Initial Comment: Hi! The IS function is used to evaluate if an expression is true, correct? It doesn't seem to like equations that are not factored out: 2*(x-(y+x))=2*x-2*(y+x); should be true, right? IS sais, it wasn't. Jonas PS: I am not an expert in CAS. If I reported complete bullshit, I would be happy about a short explanation why. thanks in advance. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-823084 ] IS often doesn't work From: SourceForge.net - 2003-10-17 06:19:07 ```Bugs item #823084, was opened at 2003-10-13 18:37 Message generated for change (Comment added) made by macrakis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 Category: Tests Group: None >Status: Closed >Resolution: Invalid Priority: 5 Submitted By: Jonas Diemer (diemer) Assigned to: Nobody/Anonymous (nobody) Summary: IS often doesn't work Initial Comment: Hi! The IS function is used to evaluate if an expression is true, correct? It doesn't seem to like equations that are not factored out: 2*(x-(y+x))=2*x-2*(y+x); should be true, right? IS sais, it wasn't. Jonas PS: I am not an expert in CAS. If I reported complete bullshit, I would be happy about a short explanation why. thanks in advance. ---------------------------------------------------------------------- >Comment By: Stavros Macrakis (macrakis) Date: 2003-10-17 02:18 Message: Logged In: YES user_id=588346 In Maxima, is(...=...) tests for *syntactic* equality: the two expressions have the same structure. To test for *semantic* equality, use equal. In your example, is(equal(2*(x-(y+x)),2*x-2*(y+x)) returns true as you'd expect. That said, in many cases is/equal cannot determine the correct result, even if other parts of Maxima can -- e.g. is (equal(sin(x)^2+cos(x)^2,1)). I agree that this is confusing, but this is the intended behavior. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-823084 ] IS often doesn't work From: SourceForge.net - 2003-10-17 12:54:31 ```Bugs item #823084, was opened at 2003-10-14 00:37 Message generated for change (Comment added) made by diemer You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 Category: Tests Group: None Status: Closed Resolution: Invalid Priority: 5 Submitted By: Jonas Diemer (diemer) Assigned to: Nobody/Anonymous (nobody) Summary: IS often doesn't work Initial Comment: Hi! The IS function is used to evaluate if an expression is true, correct? It doesn't seem to like equations that are not factored out: 2*(x-(y+x))=2*x-2*(y+x); should be true, right? IS sais, it wasn't. Jonas PS: I am not an expert in CAS. If I reported complete bullshit, I would be happy about a short explanation why. thanks in advance. ---------------------------------------------------------------------- >Comment By: Jonas Diemer (diemer) Date: 2003-10-17 14:54 Message: Logged In: YES user_id=154672 I see. Maybe somthing about testing equality etc. could go in the Primer or somewhere else... Regards ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2003-10-17 08:18 Message: Logged In: YES user_id=588346 In Maxima, is(...=...) tests for *syntactic* equality: the two expressions have the same structure. To test for *semantic* equality, use equal. In your example, is(equal(2*(x-(y+x)),2*x-2*(y+x)) returns true as you'd expect. That said, in many cases is/equal cannot determine the correct result, even if other parts of Maxima can -- e.g. is (equal(sin(x)^2+cos(x)^2,1)). I agree that this is confusing, but this is the intended behavior. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=823084&group_id=4933 ```