Banker's rounding

[sunil.thaha]

OMG !!

I am getting 8.93 on g++ 3.4.4 (linux ) and g++ (GCC) 3.4.2 (mingw-special) Windows

[matheww]

got me puzzled..

g++ -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --with-cpu=generic --host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20070502 (Red Hat 4.1.2-12)

I am using fedora core 7 x86_64

[wysota]

.5 might actually be .49999999999999 on 64b so after flooring this will be 0 Try changing the datatype (for instance to float).

BTW. For banking (or similar) you should use high precision math, for example one of these:
http://www.tc.umn.edu/~ringx004/article-main.html
http://www.nongnu.org/hpalib/
http://gmplib.org/

[matheww]

.5 might actually be .49999999999999 on 64b so after flooring this will be 0 Try changing the datatype (for instance to float).

You are right there - have been programming so long in Delphi using their Currency type that I forgot that doubles (and floats) can be a bit inaccurate, I changed the function parameter and return value to floats and i get a correct result.

BTW. For banking (or similar) you should use high precision math, for example one of these:
http://www.tc.umn.edu/~ringx004/article-main.html
http://www.nongnu.org/hpalib/
http://gmplib.org/

I will have a look at these.. really need something similar to the pascal currency type...

[jacek]

really need something similar to the pascal currency type...

See this: http://quantlib.org/