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This collection of Frequently Asked Questions (FAQs)
for CPML provides brief answers to many common questions about the
Compaq Portable Math Library. You will also find links to more detailed
information available on our site.
This is a good place to start looking for answers
to your questions. If you cannot find your answer here, please send
us email. We welcome your questions and will provide prompt
answers.
General Questions (all operating systems):
Tru64 UNIX Questions:
Linux Questions:
General Answers (all operating systems):
Q:
How do I call complex functions like cexp
and clog?
A: It is a little tricky
to call the CPML complex functions directly, because our complex
functions return their values using a private interface. The real
and imaginary parts are returned in floating registers f0 and f1.
In Fortran, there is no problem. Fortran supports
complex datatypes like COMPLEX*16. The Compaq Fortran compiler recognizes
clog and cexp, so it knows where to pick up the return values; for
example,
program call_complex
double complex w, z
double precision a, b
a = 2.0
b = 3.0
w = cmplx(a,b)
z = log(w)
print *, "log(", w, ") = ", z
end
There is no complex datatype in C - yet. C99 will
support complex numbers and complex functions. The Compaq C99 compiler
(and friends) will provide a header file with the prototypes for
the complex functions. The C99 compiler will understand how to get
the return values.
In the meantime, until C99 is available, if you want
to call complex functions from Compaq C you could try something
like the following example. This will not work on gcc or other non-Compaq
C compilers.
#pragma linkage complex_linkage = ( result (f0, f1) )
#pragma use_linkage complex_linkage ( clog )
typedef struct { double r, i; } D_COMPLEX ;
extern D_COMPLEX clog ( double, double );
main()
{
D_COMPLEX z;
double a, b, r, i;
a = 2.0;
b = 3.0;
z = clog(a, b);
r = z.r ; /* real part */
i = z.i ; /* imaginary part */
printf("clog(%f,%f) = (%f,%f)\n",a,b,r,i);
}
In the above program, you defined a struct, D_COMPLEX,
to receive the complex number that the complex function clog
computes.
The "complex_linkage" pragmas tell the
Compaq C compiler how the complex function really returns its values,
using that private interface.
Then you can just call the complex function, and
the compiler will put the returned value into the real and imaginary
members in the structure.
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Tru64 UNIX Answers:
Q:
CPML is supposed to come with Tru64 UNIX operating system,
but I cannot find it on my system. Where is CPML?
A: On Tru64 UNIX, CPML
is contained in the library /usr/lib/libm.a
and in the shared object /usr/shlib/libm.so.
If you link your application with -lm,
you are using CPML. Tru64 UNIX does not have a separate package
called CPML.
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Linux Answers:
Q:
I installed cpml_ev5/6-0.2/3
and I just did an upgrade to 0.4 or 5.0.0. There was no error message,
but now I can't find /usr/lib/libcpml.so
(or /usr/lib/cpml.h). What happened?
A: What
is happening is that after the new kit gets installed, the old kit
runs its "post-delete" script and deletes the symbolic
links.
You have to delete the old kit (using rpm
-e) and then install the new kit (using rpm
-i).
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Q:
Can I install both cpml_ev5
and cpml_ev6?
A: To use libcpml,
you only need to install one cpml package. We recommend
that you install the cpml package that matches your hardware: cpml_ev5
on ev4 and ev5 systems, cpml_ev6
on ev6 systems.
Note that the "ev6" libcpml uses a few
hardware instructions that are available only on ev6 and later systems.
Therefore, if you link your application against the libcpml.a
from the cpml_ev6 package, the application may trap when executing
on an ev4 or ev5 system.
But, if you really want to install more than one
copy of CPML on a system, please note that all cpml packages share
the following common files (symbolic links):
/usr/include/cpml.h
/usr/lib/libcpml.a
/usr/lib/libcpml.so
Because of this sharing, rpm will complain if you
do a plain installation of another cpml package.
Here is a way to install multiple cpml packages with
different version or different architecture or both:
- You should write down the current link of the shared files,
so that you can recover the links if you deinstall another cpml
package. For example:
/usr/lib/libcpml.a ->
/usr/lib/compaq/cpml-n.n.n/libcpml_ev5.a
- You can use the --replacefiles
flag to tell rpm command to overwrite
the shared files. For example:
rpm -i -vv --replacefiles cpml_ev6-n.n.n-1.alpha.rpm
- When you deinstall one of the cpml packages, restore any symbolic
links if necessary:
ln -sf /usr/lib/compaq/cpml-n.n.n/libcpml_ev5.a
/usr/lib/libcpml.a
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Q:
I just installed the cpml package, but the shared CPML library
is an empty file. Why is that?
A: During the installation,
rpm runs a script to construct the
shared CPML library. There are several possibilities why this might
fail:
- The libots rpm package might
not be installed. The shared CPML library currently requires the
libots package in order to link.
The libots rpm package is available
for free download
from the Compaq Fortran kits.
- The cpml and libots
packages were installed on the same command line but the cpml
package was listed before the libots
package.
- On Debian systems, the alien
utility that reconfigures rpm packages does not always translate
the scripts.
For preceding cases 2 and 3 and other situations where you
want to construct the shared CPML library, here is the script.
You may need to change the version numbers. For example,
cd /usr/lib/compaq/cpml-5.1.0
rm -f /usr/lib/compaq/cpml-5.1.0/libcpml_ev5.so
ld -shared -o libcpml_ev5.so -soname libcpml.so \
-whole-archive libcpml_ev5.a -no-whole-archive -lots
strip libcpml_ev5.so
/sbin/ldconfig
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