Issue #7724 has been reported by marcandre (Marc-Andre Lafortune). ---------------------------------------- Bug #7724: 6 bugs with Range#bsearch over floats https://bugs.ruby-lang.org/issues/7724 Author: marcandre (Marc-Andre Lafortune) Status: Open Priority: Normal Assignee: Category: core Target version: 2.0.0 ruby -v: r38825 Take the following code, with from, to and search all Integer or all Float: (from...to).bsearch{|f| f >= search} I expected it to: 0) never yield and return nil if range is empty, i.e. from >= to ("trivial test") 1) never yield more than 65 times for floats or Math.log(to-from, 2)+1 for Integer ("log test") 2) return search if from <= search < to, nil otherwise ("coverage test") 3) never yield the same `f` ("uniqueness test") 4) if range is exclusive, never yield `to` nor return `to`; if range is inclusive and block returns false always yield `to` ("end of range test") 5) never yield a number < from or > to ("out of range test") These conditions are all respected for Integers but all can be broken for Floats Test 0, 1, 3, 4 & 5 fail even for small ordinary float values, while test 2 requires some larger floats, say 1e100 to fail. For example bsearch can yield over 2000 times (instead of at most 65). These tests and a correct Ruby implementation of bsearch can be found here: https://github.com/marcandre/backports/compare/mar... My implementation also passes the MRI tests.
on 2013-01-22 10:49
on 2013-01-23 09:48
Issue #7724 has been updated by naruse (Yui NARUSE). Status changed from Open to Assigned Assignee set to mame (Yusuke Endoh) ---------------------------------------- Bug #7724: 6 bugs with Range#bsearch over floats https://bugs.ruby-lang.org/issues/7724#change-35544 Author: marcandre (Marc-Andre Lafortune) Status: Assigned Priority: Normal Assignee: mame (Yusuke Endoh) Category: core Target version: 2.0.0 ruby -v: r38825 Take the following code, with from, to and search all Integer or all Float: (from...to).bsearch{|f| f >= search} I expected it to: 0) never yield and return nil if range is empty, i.e. from >= to ("trivial test") 1) never yield more than 65 times for floats or Math.log(to-from, 2)+1 for Integer ("log test") 2) return search if from <= search < to, nil otherwise ("coverage test") 3) never yield the same `f` ("uniqueness test") 4) if range is exclusive, never yield `to` nor return `to`; if range is inclusive and block returns false always yield `to` ("end of range test") 5) never yield a number < from or > to ("out of range test") These conditions are all respected for Integers but all can be broken for Floats Test 0, 1, 3, 4 & 5 fail even for small ordinary float values, while test 2 requires some larger floats, say 1e100 to fail. For example bsearch can yield over 2000 times (instead of at most 65). These tests and a correct Ruby implementation of bsearch can be found here: https://github.com/marcandre/backports/compare/mar... My implementation also passes the MRI tests.
on 2013-01-23 10:43
Issue #7724 has been updated by mame (Yusuke Endoh). Assignee changed from mame (Yusuke Endoh) to marcandre (Marc-Andre Lafortune) Thanks Marc-Andre! But I'm very sorry that I'll have no enough time to pursue this issues. Could you please create a patch for C implementation? Notice that the current implementation does NOT assume that the internal representation of double is IEEE 754. Please do not depend on it but use C's constants about double, such as FLT_RADIX and DBL_MANT_DIG. -- Yusuke Endoh <mame@tsg.ne.jp> ---------------------------------------- Bug #7724: 6 bugs with Range#bsearch over floats https://bugs.ruby-lang.org/issues/7724#change-35546 Author: marcandre (Marc-Andre Lafortune) Status: Assigned Priority: Normal Assignee: marcandre (Marc-Andre Lafortune) Category: core Target version: 2.0.0 ruby -v: r38825 Take the following code, with from, to and search all Integer or all Float: (from...to).bsearch{|f| f >= search} I expected it to: 0) never yield and return nil if range is empty, i.e. from >= to ("trivial test") 1) never yield more than 65 times for floats or Math.log(to-from, 2)+1 for Integer ("log test") 2) return search if from <= search < to, nil otherwise ("coverage test") 3) never yield the same `f` ("uniqueness test") 4) if range is exclusive, never yield `to` nor return `to`; if range is inclusive and block returns false always yield `to` ("end of range test") 5) never yield a number < from or > to ("out of range test") These conditions are all respected for Integers but all can be broken for Floats Test 0, 1, 3, 4 & 5 fail even for small ordinary float values, while test 2 requires some larger floats, say 1e100 to fail. For example bsearch can yield over 2000 times (instead of at most 65). These tests and a correct Ruby implementation of bsearch can be found here: https://github.com/marcandre/backports/compare/mar... My implementation also passes the MRI tests.
on 2013-01-23 20:39
Issue #7724 has been updated by marcandre (Marc-Andre Lafortune). mame (Yusuke Endoh) wrote: > Thanks Marc-Andre! > > But I'm very sorry that I'll have no enough time to pursue this issues. > Could you please create a patch for C implementation? Sure, I'll do it. > Notice that the current implementation does NOT assume that the internal > representation of double is IEEE 754. Please do not depend on it but > use C's constants about double, such as FLT_RADIX and DBL_MANT_DIG. Actually, I don't think there is need to know how many bits are used for the mantissa vs exponent; I only need to know that double is represented with exponent bits then by mantissa bits. Apart from VAX (which had strange byte ordering, but we don't support), I believe this to be true. So floatings can be seen as [exp, mantissa], thus have the same ordering as the the corresponding integers (forgetting about the sign). I.e. (double)(++(int64_t)a_float) is the smallest float strictly greater than a_float (assuming 0 <= a_float < infinity) Do we have a list of non IEEE architectures we're hoping to support? Are there systems where sizeof(double) != sizeof(int_64_t)? ---------------------------------------- Bug #7724: 6 bugs with Range#bsearch over floats https://bugs.ruby-lang.org/issues/7724#change-35563 Author: marcandre (Marc-Andre Lafortune) Status: Assigned Priority: Normal Assignee: marcandre (Marc-Andre Lafortune) Category: core Target version: 2.0.0 ruby -v: r38825 Take the following code, with from, to and search all Integer or all Float: (from...to).bsearch{|f| f >= search} I expected it to: 0) never yield and return nil if range is empty, i.e. from >= to ("trivial test") 1) never yield more than 65 times for floats or Math.log(to-from, 2)+1 for Integer ("log test") 2) return search if from <= search < to, nil otherwise ("coverage test") 3) never yield the same `f` ("uniqueness test") 4) if range is exclusive, never yield `to` nor return `to`; if range is inclusive and block returns false always yield `to` ("end of range test") 5) never yield a number < from or > to ("out of range test") These conditions are all respected for Integers but all can be broken for Floats Test 0, 1, 3, 4 & 5 fail even for small ordinary float values, while test 2 requires some larger floats, say 1e100 to fail. For example bsearch can yield over 2000 times (instead of at most 65). These tests and a correct Ruby implementation of bsearch can be found here: https://github.com/marcandre/backports/compare/mar... My implementation also passes the MRI tests.
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