Wrappers for CBLAS and BLIS, using Guile's FFI.
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This is a set of Guile FFI bindings for CBLAS, the library of linear algebra subprograms1.
To use the bindings, import (ffi cblas)
. CBLAS will be loaded from the
default dynamic library path (see ‘Installation notes’ below). There are up to
three bindings for each function, here using ZGEMM
as an example:
cblas_zgemm
(raw binding): the raw C function by pointer->procedure
. Don't
use this if you aren't familiar with Guile's FFI.
zgemm!
(typed binding): takes array arguments of type 'c64
and operates by
effect, without making copies. All the arguments must be properly sized. The
return value is unspecified.
zgemm
(functional binding): takes array arguments of compatible types and
returns a newly constructed array. The arguments will be converted as
necessary, which may result in copies. The returned array will be of 'c64
type.
In principle, for the last two bindings, you don't need to care whether your array is row-major or column-major or what the strides are. The bindings will extract the required strides from the array arguments. However, since CBLAS doesn't support arbitrary strides (e.g. it only supports a column stride for matrix arguments, assuming column-major order), some array arguments will cause the typed binding to fail, or result in extra copies with the functional binding.
If the function doesn't return an array (e.g. sdot
) then we only provide
two bindings (e.g. cblas_sdot
and sdot
).
Enter ,help (ffi cblas)
at the Guile REPL to list all the bindings
available2.
Note that this package is a work in progress and that there are bugs. For example, negative strides require specific handling for CBLAS and are not supported yet.
guile-ffi-cblas
uses dynamic-link
to load the dynamic libraries for
CBLAS. To do this, the names of the respective library files must be
known. The default name libcblas
can be configured with the environment
variable GUILE_FFI_CBLAS_LIBNAME
. Some alternative names that I've seen are
libblas
or libatlas
.
If your CBLAS libraries are not installed in the default dynamic library
search path, you can configure specific paths for guile-ffi-cblas
with the
environment variable GUILE_FFI_CBLAS_LIBPATH
. There are other variables that
control where dynamic-link
searches for libraries (LTDL_LIBRARY_PATH
,
LD_LIBRARY_PATH
) and you may prefer to set those instead. See also
https://notabug.org/ZelphirKaltstahl/guile-ml#using-guile-ffi-cblas
for notes on using guile-ffi-cblas
on Guix3.
The tests use SRFI-64.
$GUILE -L mod -s test/test-ffi-cblas.scm
Depending on your installation (see above) you might need
GUILE_FFI_CBLAS_LIBNAME=libotherblas \
GUILE_FFI_CBLAS_LIBPATH=/custom/path/lib \
$GUILE ... etc.
srotg
drotg
crotg
zrotg
4sscal
dscal
cscal
zscal
csscal
zdscal
sswap
dswap
cswap
zswap
scopy
dcopy
ccopy
zcopy
saxpy
daxpy
caxpy
zaxpy
sdot
ddot
cdotu
zdotu
cdotc
zdotc
snrm2
dnrm2
scnrm2
dznrm2
sasum
dasum
scasum
dzasum
isamax
idamax
icamax
izamax
sgemv
dgemv
cgemv
zgemv
sger
dger
cgeru
zgeru
cgerc
zgerc
sgemm
dgemm
cgemm
zgemm
¹ See http://www.netlib.org/blas/ or https://en.wikipedia.org/wiki/Basic_Linear_Algebra_Subprograms. ↩
² Unfortunately this triggers a bug in the current version. ↩
³ A previous version of this library also included BLIS
bindings, but now I have moved those to a separate library
(guile-ffi-blis
). ↩ .
⁴ Some distributions of libcblas
do not provide
these. guile-ffi-cblas
will still work, just without these bindings.