Dear Jirka, Out of curiosity, I tested both the -m96bit-long-double and the -m128bit-long-double on my Intel box ... and both of them are 80-bit IEEE 754 numbers. The former with 16-bits fallow (or 2 pad bytes), the latter with 48-bits fallow (or 6 pad bytes). The -m128bit-long-double option is useful for alignment issues, NOT for improved mantissa precision nor exponent range. Both -m96bit-long-double and -m128bit-long-double had the same test results for exponent and mantissa sizes... float : exp:8 mant:23+1 double : exp:11 mant:52+1 long double : exp:15 mant:64 (The "+1" on the mantissa is if there is an implicit "hidden" most-significant bit.) If you are curious as to the actual Intel memory layout of these different formats, I can dummy up a little ASCII art. Let me know. IEEE 754 terminology for (typical) C/C++ float / double / long double is single / double / extended. More info at... <http://babbage.cs.qc.edu/courses/cs341/IEEE-754references.html> HTH, --Eljay
