July 2006 - Boost-users - lists.preview.boost.org

uBlas matrix * matrix operation
by Dave Steffen 26 Jul '06

26 Jul '06

Hi Folks, This is my first excursion into uBlas. I'm getting an "ambiguous overload for 'operator*' in 'a * b' " sort of error out of this: #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/matrix_expression.hpp> namespace UB { using namespace boost::numeric::ublas; template <int N> struct Type { typedef matrix<double, row_major, bounded_array<double, N*N> > matrix; }; } // elsewhere... typename UB::Type<N>::matrix a(N,N), b(N,N); for (int i = 0; i < N; ++i) for (int j = 0; j < N; ++j) { a(i,j) = 1.0 / (i + j+1); b(i,j) = 1.0 / (i + j+1); } a * b; The error (from GCC 3.4.6) is this ugly thing: /usr/local/home/dgsteffen/local/GCC34/Boost/1_32/boost/numeric/ublas/matrix_expression.hpp:3632: note: candidates are: typename boost::numeric::ublas::matrix_binary_scalar2_traits<E1, const T2, boost::numeric::ublas::scalar_multiplies<typename E1::value_type, T2>, boost::numeric::ublas::scalar_reference<const T2> >::result_type boost::numeric::ublas::operator*(const boost::numeric::ublas::matrix_expression<E>&, const T2&) [with E1 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >, T2 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >] /usr/local/home/dgsteffen/local/GCC34/Boost/1_32/boost/numeric/ublas/matrix_expression.hpp:3162: note: typename boost::numeric::ublas::matrix_binary_scalar1_traits<const T1, E2, boost::numeric::ublas::scalar_multiplies<T1, typename E2::value_type>, boost::numeric::ublas::scalar_reference<const T1> >::result_type boost::numeric::ublas::operator*(const T1&, const boost::numeric::ublas::matrix_expression<E2>&) [with T1 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >, E2 = boost::numeric::ublas::matrix<double, boost::numeric::ublas::row_major, boost::numeric::ublas::bounded_array<double, 441u, std::allocator<double> > >] Any thoughts on what I'm doing wrong? Thanks! ---------------------------------------------------------------------- Dave Steffen, Ph.D. Software Engineer IV Disobey this command! Numerica Corporation ph (970) 419-8343 x27 fax (970) 223-6797 - Douglas Hofstadter dgsteffen(a)numerica.us ___________________ Numerica Disclaimer: This message and any attachments are intended only for the individual or entity to which the message is addressed. It is proprietary and may contain privileged information. If you are neither the intended recipient nor the agent responsible for delivering the message to the intended recipient, you are hereby notified that any review, retransmission, dissemination, or taking of any action in reliance upon, the information in this communication is strictly prohibited, and may be unlawful. If you feel you have received this communication in error, please notify us immediately by returning this Email to the sender and deleting it from your computer.

1 0

How to cast form string to number safely?
by 袁晓辉 26 Jul '06

26 Jul '06

Dear boost-users: I am really sorry for asking shch a silly question, but I really need your help! boost::lexical_cast is a great function to do casting. If I want is to cast from string to a "long long" type value, I can use the follow: long long llVar = lexical_cast<long long>("123456789"); It is alright in this circs, but what if: lexical_cast<long long>("9999999999999999999999999999999999999999999999999999999999999999999999999999"); This is an obvious overflow, but I have no way to handle this error, it returns a wrong number without throwing an exception! Any suggestion? Thank you very much!!! Kevin

4 5

Re: [Boost-users] shared_ptr and inheritance of the raw pointer
by Nat Goodspeed 26 Jul '06

26 Jul '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Yossi.Itzkovich(a)ecitele.com > Sent: Wednesday, July 26, 2006 3:03 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] shared_ptr and inheritance of the raw pointer > > I have this code: > > #include <boost/shared_ptr.hpp> > > class A{ // base class > public: virtual ~A(); // otherwise A isn't polymorphic, can't downcast > }; > > class B : public A{ > public: > int b1; > }; > > typedef boost::shared_ptr<A> tSmartA; > typedef boost::shared_ptr tSmartB; > > void foo (const tSmartB& smartOne); // need ; for syntax ^^^^^ permits passing an expression > > int main () { > tSmartA a(new B); foo(boost::dynamic_pointer_cast(a)); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > return 0; > } > > > How can I then send a to foo() ? [Nat] With the three changed lines shown above, this compiles for me under MSVC 7.1.

1 0

Boost MultiIndex container - using multiple composite keys
by Charitha Herath 26 Jul '06

26 Jul '06

Hi All, I'm new to this mailing list. I have been using the boost multi index container for a while. I now have requirement where I need to create multiple composite keys. The example 7 (composite keys example) in the multi index container documentation shows that it is possible to define multiple composite keys. But how do we use a specific composite key when searching the data. Does the container differentiate the composite keys using the key data types? Thanks, Charitha --------------------------------- How low will we go? Check out Yahoo! Messengers low PC-to-Phone call rates.

2 1

shared_ptr and inheritance of the raw pointer
by Yossi.Itzkovich＠ecitele.com 26 Jul '06

26 Jul '06

Hi, I have this code: #include <boost/shared_ptr.hpp> class A{ // base class public: }; class B : public A{ public: int b1; }; typedef boost::shared_ptr<A> tSmartA; typedef boost::shared_ptr tSmartB; void foo (tSmartB& smartOne) // should get a pointer to derived { } int main () { tSmartA a(new B); foo(a); // This line doesn't compile because foo expects to get tSmartB return 0; } How can I then send a to foo() ? Thanks Yossi

2 1

[Lambda] find_if + vector of arrays
by Sohail Somani 25 Jul '06

25 Jul '06

Hi, Why can't lambda figure out the return type of operator[] for array? Does it know about vectors? I know I can fix the compile error by using bl::ret<double>(bl::_1[0])... But for obvious reasons, I'd much rather not! #include <vector> #include <algorithm> #include <boost/array.hpp> #include <boost/lambda/lambda.hpp> int main() { namespace bl=boost::lambda; using std::vector; using boost::array; array<double,3> cpy = {1}; vector<vector<double> > a(10,vector<double>(3,1)); vector<array<double,3> > b(10,cpy); std::find_if(a.begin(),a.end(),bl::_1[0]==5); std::find_if(b.begin(),b.end(),bl::_1[0]==5); } Thanks! Sohail

1 0

Re: [Boost-users] [serialization] Skipping unexpected elements inXMLarchive
by Todd Greer 25 Jul '06

25 Jul '06

Robert Ramey wrote: > Sounds to me that others might find this useful. How about making a > little write up, and maybe a small test/demo, zipping it up and uploading > to the serialization section of the boost vault? I'll do that. Unfortunately, I noticed that I use putback twice in a row, which I understand is not guaranteed to work. I'm working on fixing that now, and will put the code in the vault once that's fixed. I've fixed a couple of other things as well, and will include those fixes in the vault upload. -- Todd Greer <tgreer <at> affinegy dot com> Senior Software Developer, Affinegy LLC

1 0

reading data into vector/matirx
by Fred J. 25 Jul '06

25 Jul '06

dear boost users is there a library where it will take a file name and gives a vector/matrix of the data in the file. data formate is space delimited name age location hairColour thanks --------------------------------- Do you Yahoo!? Get on board. You're invited to try the new Yahoo! Mail Beta.

1 0

Grep() question
by Winson Yung 25 Jul '06

25 Jul '06

Hello all, I have the following regular expression, but it doesn't match to this text "REVENUE ................................................... $10,481.1" const char* pattern[] = "Revenue[\s\.]*\$?\s*([0-9,\.]*)"; my code looks something like this: std::vector <unsigned int> v; boost::RegEx expr(pattern, true); v.clear(); unsigned int result = expr.Grep(v, pBuf); if (result != 0) { std::string s = expr[0]; s = expr[1]; ............ Why expr[0] and expr[1] weren't return the aboved mention text as the first match? I think set 'true' in expr constructor means do case insensitve match. /Winson.

2 7

Newbie String Splitting Question
by Seth Nielson 25 Jul '06

25 Jul '06

Hi Two questions related to string tokenization. 1. Which is preferred? using "split" or the "tokenizer class"? 2. Both of these methods seem geared towards splitting on characters rather than splitting on substrings. Is there yet another method that is preferred for splitting a string on an exact substring? If I want to split "IAmATest" into I, Am, A, Test, what is the best way? It seems that for split I'll have to write my own predicate, and for tokenizer, I'll have to write my own tokenizerFunction. -- Seth N.

7 11