John Maddock wrote:
Could any one confirm if it is an error indeed?
These all look to be related, and indicate a genuine issue:
fabs(long_double_value)
is returning a double (ie truncated) result :-(
Can you confirm whether #include <cmath> results in fabs(long double) being defined?
John, I made quick test and it looks std::fabs(long double) is missing: $ cat long_double_fabs.cpp #include <cmath> template <typename T> T foo(T a, T b) { return a + b; } int main() { long double a = -1.23; long double b = std::fabs(a); // compiles foo( std::fabs(a), b ); // does not compile } $ como --strict --c++ long_double_fabs.cpp Comeau C/C++ 4.3.10.1 (May 7 2008 12:23:21) for LINUX_INTEL_ELF_Beta Copyright 1988-2008 Comeau Computing. All rights reserved. MODE:strict errors C++ noC++0x_extensions "long_double_fabs.cpp", line 11: error: no instance of function template "foo" matches the argument list argument types are: (double, long double) foo( std::fabs(a), b ); // does not compile ^ 1 error detected in the compilation of "long_double_fabs.cpp". The <cmath> comes from libcomo library: /opt/libcomo36/include/cnames/cmath and it includes <math.h> from GNU C Library. I generated raw listing (preprocessed, etc.) and it looks that actual definition of fabs being used comes from GNU C Library and it truncates input argument to double: /* Absolute value of X. */ __MATHCALLX (fabs,, (_Mdouble_ __x), (__const__)); It may look like Comeau/libcomo issue, as long double fabs(long double) should be well defined so the simple template test above is supposed to work. Am I correct? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org