Christian Schoenebeck writes: > Am Donnerstag, 27. April 2006 11:20 schrieb zerenz@xxxxxxxxxx: > > We want to compile a Fluent UDF function in which we need to define a > > complex variable. However we couldnt find how to. Could you please show us > > a way? > > Now as you say it, I thought I remembered a "complex" type gcc extension as > well, but couldn't find it either. TFM! :-) 5.9 Complex Numbers ISO C99 supports complex floating data types, and as an extension GCC supports them in C89 mode and in C++, and supports complex integer data types which are not part of ISO C99. You can declare complex types using the keyword `_Complex'. As an extension, the older GNU keyword `__complex__' is also supported. For example, `_Complex double x;' declares `x' as a variable whose real part and imaginary part are both of type `double'. `_Complex short int y;' declares `y' to have real and imaginary parts of type `short int'; this is not likely to be useful, but it shows that the set of complex types is complete. To write a constant with a complex data type, use the suffix `i' or `j' (either one; they are equivalent). For example, `2.5fi' has type `_Complex float' and `3i' has type `_Complex int'. Such a constant always has a pure imaginary value, but you can form any complex value you like by adding one to a real constant. This is a GNU extension; if you have an ISO C99 conforming C library (such as GNU libc), and want to construct complex constants of floating type, you should include `<complex.h>' and use the macros `I' or `_Complex_I' instead. To extract the real part of a complex-valued expression EXP, write `__real__ EXP'. Likewise, use `__imag__' to extract the imaginary part. This is a GNU extension; for values of floating type, you should use the ISO C99 functions `crealf', `creal', `creall', `cimagf', `cimag' and `cimagl', declared in `<complex.h>' and also provided as built-in functions by GCC. The operator `~' performs complex conjugation when used on a value with a complex type. This is a GNU extension; for values of floating type, you should use the ISO C99 functions `conjf', `conj' and `conjl', declared in `<complex.h>' and also provided as built-in functions by GCC. GCC can allocate complex automatic variables in a noncontiguous fashion; it's even possible for the real part to be in a register while the imaginary part is on the stack (or vice-versa). Only the DWARF2 debug info format can represent this, so use of DWARF2 is recommended. If you are using the stabs debug info format, GCC describes a noncontiguous complex variable as if it were two separate variables of noncomplex type. If the variable's actual name is `foo', the two fictitious variables are named `foo$real' and `foo$imag'. You can examine and set these two fictitious variables with your debugger. Andrew.
