Hi Alex,
one more 'native' question, this time a bit more complicated:
libblas.so is on my machine, the C function "idamax_" is found,which is
actually a C wrapper for Fortran Code.
In the Fortran docs, the parameters are described exactly, see below.
Since the Parameters of the C function are input/output Parameters, I try
to define the input values in the CDDR, but obviously not correctly.
How do I define an input array correctly (especially DX and INCX)?
If I have in/out Parameters, how do I get the int return value too when the
pil functions returns?
hope these questions are not too messy ...
cheers
Thorsten
PS
when I understand how this works, I will use the input values for native as
parameters for the pil wrapper, but for now I just write them inside of
'native'.
*> \param[in] N
33 *> \verbatim
34 *> N is INTEGER
35 *> number of elements in input vector(s)
36 *> \endverbatim
37 *>
38 *> \param[in] DX
39 *> \verbatim
40 *> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
41 *> \endverbatim
42 *>
43 *> \param[in] INCX
44 *> \verbatim
45 *> INCX is INTEGER
46 *> storage spacing between elements of DX
47 *> \endverbatim
48 *
(symbols 'blas 'pico)
(default *LibBlas "libblas.so")
(de idamax ()
(use "N" "Dx" "Incx"
(native `*LibBlas "idamax_" 'I '("N" (4 . 'I) 3) '("Dx" (8 . 1.0)
'(1.0 1 2 3)) '("Incx" (4 . 'I) 0)) (list "N" "Dx" "Incx") )
)
## BLAS_extern int /* IDAMAX - return the index of the element with
max abs value */ ## F77_NAME(idamax)(const int *n,
const double *dx, const int *incx)
# when INCX = 0
: (blas~idamax)
-> ('NIL 0 'NIL)
# when INCX = 1 segfault
Am Di., 17. Nov. 2020 um 23:45 Uhr schrieb Thorsten Jolitz <
[email protected]>:
> Hi Alex,
> the wrappers with primitive arguments do work now when defined like this
> with transient symbols:
>
> (de pgamma ("X" "Y" "Z" "I" "J")
> (native `*LibRmath "pgamma" 1.0 (cons "X" 1.0) (cons "Y" 1.0) (cons
> "Z" 1.0) "I" "J" ) )
> ## double› pgamma(double, double, double, int, int);
>
> With your tips I could define wrappers for functions with pointer args too
>
> (de pnorm_both ("X" "I" "J")
> (use "Y" "Z"
> (native `*LibRmath "pnorm_both" NIL (cons "X" 1.0) '("Y" (8 .
> 1.0)) '("Z" (8 . 1.0)) "I" "J" )
> (list "Y" "Z") ) )
> ## void› pnorm_both(double, double *, double *, int, int);/* both
> tails */
>
> does work (scl 3):
> : (rmath~pnorm_both 1.2 2 3)
> -> (-122 -2162)
>
> now I only have to understand the meaning of some of these functions.
> What I find irritating is that the pointer args are not used for input but
> only as a kind of return values.
>
> Thanks for your help!
> Cheers
> Thorsten
>
> Am So., 15. Nov. 2020 um 22:55 Uhr schrieb Alexander Burger <
> [email protected]>:
>
>> Hi Thorsten,
>>
>> hmm, this is not correct:
>>
>> > (de pnorm_both ("X" "Y" "Z" "I" "J")
>> > (! native `*LibRmath "pnorm_both" 1.0 (cons "X" 1.0) '("Y" (1.0 .
>> 4))
>> > '("Z" (1.0 . 4)) "I" "J" ) )
>>
>> "Z" is an argument to the function, so it is bound to some evaluated
>> value.
>>
>> But this value is ignored, because in
>>
>> '("Z" (1.0 . 4))
>>
>> "Z" is a *return* value. Also, (1.0 . 4) makes no sense here. A structure
>> argument is
>>
>> '(Var (<size> . <returnSpec))
>>
>> but 1.0 is no size (it is too big, something like 1000000) and 4 is no
>> return
>> spec.
>>
>>
>> If you want to pass a buffer to receivea double (the double* in the C
>> signature), you would do:
>>
>> (use MyDouble
>> (native `*LibRmath "pnorm_both" 1.0 ...
>> '(MyDouble (8 . 1.0)) ... )
>> ... do something with MyDouble ...)
>>
>> (8 . 1.0) allocates 8 bytes on the stack, passes the pointer to the C
>> function,
>> receives a double in this place, and stores it in the symbol MyDouble.
>>
>> ☺/ A!ex
>>
>> --
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>>
>
