June 2004 - Boost - lists.boost.org

RE: [boost] Re: Re: Re: Boost Mathematicians
by Hurd, Matthew 04 Jun '04

04 Jun '04

> Behalf Of Thorsten Ottosen > > > "Hurd, Matthew" <hurdm(a)sig.com> wrote in message <snip> > See Type-Based Alias Analysis: > > http://www.ddj.com/documents/s=880/ddj0010d/0010d.htm?temp=fXniOPb1aS Thanks for the link. > > I my suggestion for Design by Contract I mentioned that aliasing (or lack of > it) > could be expressed by a function precondition: > > void foo( T* l, T* r, size_t sz ) > precondition() { > std::less<T*>( l + sz, r ) || std::less<T*>( r + sz, l ); > }; That's ok for simple contiguous spaces but it becomes intractable with complex object collections, but then perhaps the efficiency probably ain't so important as you've lost the locality anyway. > | You still need to wrap as you can't hope, nor should you try, to offer > | all algorithms from all languages. > > probably not. But simply wrapping stuff is not always an option. For eaxample, > in the > statistics lib I'm working on, I need to invert matrices. If I write wrappers, > I will > probably only be ably to support float,double,complex leaving out higher > precsion > datatypes. Yup. Generic interface first. Implementation with ublas where possible. Other generic implementations. Specialize for performance I guess. I haven't looked at uBLAs for a while but there was an interface to ATLAS for performance and also a partial wrapper for LAPACK. Not sure if the use of ATLAS or otherwise is or can be made to be automatic at compile time, but this would give us most of what we need. Generic implementations with pluggable special high performance specializations wherever possible. Regards, Matt Hurd. _______________ Matt Hurd +61.2.8226.5029 hurdm(a)sig.com Susquehanna _______________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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RE: [boost] Proposed Boost Library for Data Series Analysis
by Hurd, Matthew 04 Jun '04

04 Jun '04

> Behalf Of Tom Brinkman > Sounds very powerful. Is there any additional web > information to help me incorporate > these ideas. Not that I know of, but it isn't overly original in approach. Most interactive tools, such as a spreadsheet, will have something like a DAG structure at their core to represent a model-view type dependency thingo. Wish I had more time to play with this stuff... Regards, Matt Hurd. _______________ Matt Hurd +61.2.8226.5029 hurdm(a)sig.com Susquehanna _______________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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RE: [boost] [assignment library post review]
by Rozental, Gennadiy 04 Jun '04

04 Jun '04

> The post review version can be downloaded from > http://tinyurl.com/38c7d Could you please clean archive from garbage in test directory. Gennadiy.

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RE: [boost] [assignment library post review]
by Max Khesin 04 Jun '04

04 Jun '04

Thorsten, link's dead. > -----Original Message----- > From: Thorsten Ottosen [mailto:nesotto@cs.auc.dk] > Sent: Thursday, June 03, 2004 1:08 PM > To: boost(a)lists.boost.org > Subject: [boost] [assignment library post review] > > > Dear All, > > The post review version can be downloaded from > > http://tinyurl.com/38c7d This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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Proposed Boost Library for Data Series Analysis
by Tom Brinkman 04 Jun '04

04 Jun '04

I've created a library for data series calculation and analysis. I've received permission to open-source the library and I would like to submit it for review to the boost if there is sufficient interest. Simple Example 1: Calculate the 10-day simple-moving-average of the 15 exponential-moving-average. (Demonstrates: boost::algorithm::compose). std::vector<double> v1; v1 += 3,4,4,6,7,8,4,7,8,3,2,3,2,5; typedef boost::algorithm::compose<double, boost::function<double (double)>, boost::function<double (double)> > COMPOSE; std::vector<double> v; std::transform(v1.begin(), v1.end(), std::back_inserter(v), COMPOSE(moving_average(15), exponential_moving_average(10))); Simple Example 2 (contrived): * Add 100 to the results from above. * then divide by 100, * then subtract by 100, * then multiply by 100. std::vector<double> v1; v1 += 3,4,4,6,7,8,4,7,8,3,2,3,2,5; typedef boost::algorithm::compose<double, boost::function<double (double)>, boost::function<double (double), boost::function<double (double), boost::function<double (double)> > COMPOSE2; std::vector<double> v2; std::transform(v.begin(), v.end(), std::back_inserter(v2), COMPOSE2(_1 += 100, _1 /= 100, _1 -= 100, _1 *= 100)); Here is a paritial list of functors currently provided by the library. Many additional functors have been written but are fairly specific to our problem domain. moving_average triangle_moving_average rate_of_change momentum vertical_horizontal_filter volatility weighted_moving_average exponential_moving_average variable_moving_average accumulate_n relative_strengh_index cumulative_sum max_numeric_limit variance standard_deviation correlation z_score Please tell me if there is any interest in this library. I will boostify it and submit it for review if there is sufficient interest. Regards, Tom Brinkman __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/

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boost/format/format_class.hpp workaround for aC++
by DY, JERRY U (SBCSI) 03 Jun '04

03 Jun '04

Would the experts let me know if there's a better way of accomplishing the same effect below? I have modified boost/format/format_class.hpp and added a line 93 (See attached) && !BOOST_WORKAROUND( __HP_aCC, != 0) <<format_class.hpp>> Thanks! -Jerry

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RE: [boost] [assignment library post review]
by Rozental, Gennadiy 03 Jun '04

03 Jun '04

> The post review version can be downloaded from > > http://tinyurl.com/38c7d Does not work Gennadiy

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RE: [boost] static sized strings
by Reece Dunn 03 Jun '04

03 Jun '04

Martin wrote: >I have tested the sandbox version of the static sized strings. It works >fine >but there are a few inconveniences that I want to point out. I have been writing a series of test cases (boost-sandbox/libs/test) and fixing several bugs. Have you tried these? Also, what compiler(s) are you using? >1. The abstract base class. >--------------------------- >Having an ABC to handle fixed strings of various lengths is a good idea but >it >is not very practical. I understand that the main purpose is to allow fixed >strings to be passed to functions without using templates. > >int countwords(const boost::char_string & str); > >unfortunatly the ABC makes it difficult to pass anything but fixed strings. >If >you want to pass a string literal, a character array or a std::string you >must >create a temporary fixed_string<>. > >countwords(boost::fixed_string<20>("The quick brown fox")); This is an unfortunate side-affect of using the ABC technique that affects John's implementation as well. Your proposed solution looks interesting, but I don't know how practical it will be for the string manipulation operations (w.r.t. buffer safety). Rob proposed a "make_string" function, which would simplify this a little. >2. Substrings >------------- >One of the applications I can see for fixed_string is when you want to >avoid >dynamic allocation but still want to use the std::string interface and >algorithms. In that perspective it seems strange that substr returns a >std::string instead of a fixed_string. This is related to the above problem. You cannot create an instance of boost::char_string, etc. and as such cannot implement substr in the usual way (this is the proplem I was having with operator+). The solution would be to defione an alternate substr function in fixed_string, but this would not solve the problem for boost::char_string, etc. The alternative would be to use a ranged string (pointer to the fixed_string buffer and length), but the problem with this is null-termination. I do not see an easy way around this without removing the ABC design, since it is not possible to do fixed_string< length() > or something similar. >3. resize >--------- >Still missing a method to update the length to reflect the current string >length. I think a resize without arguments would be a good solution. > >boost::fixed_string str<10> >strtime(str.buffer()); >str.resize(); I'll add this soon. I have mainly been focusing on getting documentation and the test cases up. >4. operator[] >------------------------- >I don't have the standard basic_string interface available but I am pretty >sure that operator[] doesn't throw an exception if the argument is outside >max_size(). This is a deviation from the standard. If i > capacity() then the index will be out of the string buffer range and a buffer overrun can occur. This generates an exception to prevent the overrun. I should add this to the docs. Regards, Reece _________________________________________________________________ Express yourself with cool new emoticons http://www.msn.co.uk/specials/myemo

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Re: [boost] Re: static sized strings
by Reece Dunn 03 Jun '04

03 Jun '04

Rob Stewart wrote: >From: "Reece Dunn" <msclrhd(a)hotmail.com> > > Rob Stewart wrote: > > >From: "Reece Dunn" <msclrhd(a)hotmail.com> > > > > John Nagle wrote: > > [snip] > > I think you misunderstand what I am trying to say. See my comments >below. > >Actually, I think you misunderstood my points. ok. > > [1] You need to specify the size of the buffer. You cannot declare an >object > > of type fixed_string_base (as it is abstract), you can only have >references > > and pointers to it so you can operate on variable-capacity strings. > >Ah, but you missed that I was declaring a fixed_string_base, >where string capacity is not known. I was relying on >make_fixed_string() to deduce the array length and create an >appropriate fixed_string for it. I didn't miss it, just misunderstood what you intended. > > [2] This is the point that we are discussing. Should this line be: > > > > fixed_string< LENGTH > t; > > > > as will work with the current sandbox implementation (my suggestion #2), >or > > should it be: > > > > fixed_string< LENGTH + 1 > t; > >And that's exactly my point. It should be the former as shown by >my equivalencies. > > > Different programmers favour the different semantics, so I ask: why not > > parameterise it, providing a default behaviour. > >I'm not so sure they do and I'm not sure you need to allow for >it. If you do, I suspect you'll encourage off-by-one mistakes. >Granted, those mistakes won't result in overruns, but they will >be annoying. Furthermore that will result in different >fixed_string types; will you provide for conversions among them? >(That is, for example, from a fixed_string that adds one to the >capacity to one that doesn't?) It is the former in the implementation I have, but if you have char data[ 100 ]; // manipulate and use the data buffer in this example, the buffer is 100 characters, but only 99 are writable, with the 100th being a null character (assuming this is a C-style string). Using the current implementation, this would lead to fixed_string< 100 > data; having an extra character. This would transfer to the other model. > > >(I know there is no make_fixed_string() -- yet -- but such a > > >facility would be appropriate.) > > > > Er... the fixed_string constructors! When you declare the object, you >should > > know the size of the buffer you are using, e.g.: > > > > fixed_string< 100 > data; > >The problem is that you don't know the length of the string. >That is, with this code: > > char s[] = "1234"; > >s is a fixed size array of char with five elements. The >programmer didn't have to write: > > char s[5] = "1234"; > >Instead, the compiler figured out the length. > >That's what I'm trying to provide an equivalence for: > > fixed_string_base & s = make_fixed_string("1234"); > >With that approach, the client doesn't need to precompute the >length of the literal and can rely on the compiler (and template >magic) to deduce it and use it to create a fixed_string<5>. > >I've shown returning by value (with the temporary bound to the >reference s), but it could return a smart pointer just as well. Your original example didn't have fixed_string_base as a reference. It should be easy to implement a make_fixed_string function. > > >I think this clearer reveals that fixed_string's size parameter > ^^^^^^^ >That should have been "clearly." > > > >should specify the number of characters. Remember, one can use > > >boost::array to manage a fixed size, non-string buffer. If > > >buffer overrun protection is insufficient in boost::array, that > > >should be fixed (or a new class should be added to Boost). Thus, > > >fixed_string can ignore that usage. I am not disputing this. The question is, is the null terminator counted as a character. For the example you show, it is, but for buffers (see the example above) it isn't. I haven't got a conversion between the two models because I am only implementing the one model at the moment, but conversion would be automatic because the functions that take strings as arguments take fixed_string_base & arguments, so they should be usable regardless, consider: boost::fixed_string< 20 > str1( "This is a long string!" ); boost::fixed_string< 10 > str2; str2.assign( str1 ); This will work (cutting the string short in str2) even though the strings are of different capacities. Regards, Reece _________________________________________________________________ Express yourself with cool emoticons - download MSN Messenger today! http://www.msn.co.uk/messenger

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A question on serialization library
by Virendra Verma 03 Jun '04

03 Jun '04

If a class has a pointer to an object, how does class know that the pointer was created by library or the class itself before serialization?

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