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March 2012

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construction of cl_F from long double
by GiulianoDammando＠libero.it 22 Mar '12

22 Mar '12

Hi, i'm getting the following error when using the cln::cl_float function with a long double argument lanczos.cpp:4119:70: error: call of overloaded ‘cl_float(long double, const cln::float_format_t&)’ is ambiguous /opt/local/include/cln/float.h:69:19: note: candidates are: const cln::cl_F cln::cl_float(const cln::cl_F&, const cln::cl_F&) /opt/local/include/cln/float.h:76:19: note: const cln::cl_F cln::cl_float(const cln::cl_F&, cln::float_format_t) /opt/local/include/cln/float.h:90:19: note: const cln::cl_F cln::cl_float(const cln::cl_I&, const cln::cl_F&) /opt/local/include/cln/float.h:97:19: note: const cln::cl_F cln::cl_float(const cln::cl_I&, cln::float_format_t) /opt/local/include/cln/float.h:110:19: note: const cln::cl_F cln::cl_float(const cln::cl_RA&, const cln::cl_F&) /opt/local/include/cln/float.h:117:19: note: const cln::cl_F cln::cl_float(const cln::cl_RA&, cln::float_format_t) /opt/local/include/cln/float.h:126:19: note: const cln::cl_F cln::cl_float(int, const cln::cl_F&) /opt/local/include/cln/float.h:128:19: note: const cln::cl_F cln::cl_float(unsigned int, const cln::cl_F&) /opt/local/include/cln/float.h:130:19: note: const cln::cl_F cln::cl_float(int, cln::float_format_t) /opt/local/include/cln/float.h:132:19: note: const cln::cl_F cln::cl_float(unsigned int, cln::float_format_t) /opt/local/include/cln/float.h:139:19: note: const cln::cl_F cln::cl_float(float, const cln::cl_F&) /opt/local/include/cln/float.h:141:19: note: const cln::cl_F cln::cl_float(double, const cln::cl_F&) /opt/local/include/cln/float.h:143:19: note: const cln::cl_F cln::cl_float(float, cln::float_format_t) /opt/local/include/cln/float.h:145:19: note: const cln::cl_F cln::cl_float(double, cln::float_format_t) /opt/local/include/cln/real.h:51:19: note: const cln::cl_F cln::cl_float(const cln::cl_R&, const cln::cl_F&) /opt/local/include/cln/real.h:58:19: note: const cln::cl_F cln::cl_float(const cln::cl_R&, cln::float_format_t) suppose this is due to a missing constructor for the long double type. I would like to know if there is any fix to this problem allowing to preserve the larger precision of the long double compared to double. Thanks in advance, Giuliano

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Re: [CLN-list] I applied the patch
by Richard B. Kreckel 19 Mar '12

19 Mar '12

Hi! On 03/12/2012 05:53 PM, Alessandro PROFETI wrote: > I wasn't very fast in downloading cln source code and applying the patch. > Without the patch, the number in the last incomplete (no \n) line wasn't > read by cin >> x. > Now the behavior of operator>> is the same, the last number is read and > printed in both > cases; the next cin>>x results in an exception. > This behavior is EXACTLY what I observe when x is a double, if I compile > the file profeti.cc with the switch -DEXCEP. Great. So that is fixed now. I've committed it. > Is there a way for asking cln to behave the same way as c++ when > extracting a cl_R, > so that the code > sum = 0; > while (cin >> x) > sum = sum + x; > would compute the sum of the data, with x double or x in cl_R? > This way of coding is much simpler then > for (;;) > { > try { > cin >> x; > } catch ( ... ) { > break; > } > sum = sum + x; > } Good point. I agree that, ideally, CLN would behave the same as standard C++ when reading numbers from streams. Another issue is reading from an input stream that provides "123ABC". It seems like standard C++ reads 123 and stops there while CLN reads more and later discovers that ABC doesn't match the format. > I tried to peep in cln source code and in the code for libstdc++, but > couldn't figure out > if there is some place in cln code when one can take in account the > value of cin.exceptions() > and react to error throwing an exception when the corresponding bit is set > or returning a null reference (the default for cin >> x when x is > double) when the bit is clear. I think rather than resetting exceptions after the fact, the functions implemented in cl_*_read_stream.cc should be written to be more specific to the number format. They could then read only what is required. I'll see if I can provide a patch. Bye! -richy. PS: I'm taking this thread to the mailing list. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

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