我想从Raku调用一个C函数https://github.com/wch/r-source/blob/trunk/src/nmath/rmultinom.c#L47。为此，我将Raku函数定义为

use NativeCall;
constant RMATH = "./Rmath.dll";
multi set_seed(uint32, uint32)
    is native( RMATH ) { * };
multi set_seed(UInt() $a, UInt() $b) is export {
    set_seed(my uint32 $ = $a, my uint32 $ = $b)
}
sub rmultinom(int32, CArray[num64], int32, CArray[int32])
    is native( RMATH ) { * }; 

sub raku_rmultinom($n , $size, @prob is copy) is export {
    @prob = @prob.map: {$_.Num};
    my $prob = CArray[num64].new(@prob);
    my $ints = CArray[int32].allocate($size);
    rmultinom($n, $prob, $size, $ints);
    return $ints.list
}

字符串
电话

my @prob = [0.1, 0.3, 0.5, 0.1];
set_seed(123,456);
say raku_rmultinom(100, 5, @prob);

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给

(9 29 49 13 0)

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• 符合 * C代码：

#define MATHLIB_STANDALONE 1
#include "Rmath.h"
#include <stdio.h>

int main(int argc, char** argv) {
    int draws = 100;
    int classes = 5;
    int vals[classes];
    double probs[4] = {0.1, 0.3, 0.5, 0.1};

    set_seed(123, 456);
    rmultinom(draws, probs, classes, vals);

    for(int j=0; j < classes; j++) {
        printf("Count of class %i drawn: %i\n", j, vals[j]);
    }
    return 0;
}

Count of class 0 drawn: 9
Count of class 1 drawn: 29
Count of class 2 drawn: 49
Count of class 3 drawn: 13
Count of class 4 drawn: 0

但是当我将大小增加到10时，请参见下面的示例，输出似乎很奇怪：

my @prob = [0.1, 0.3, 0.5, 0.1];
set_seed(123,456);
say raku_rmultinom(100, 10, @prob);

(0 0 0 0 0 -1 0 0 0 0) # expectation was (9 29 49 13 0 0 0 0 0 0)

的字符串
在C中：

int main(int argc, char** argv) {
    int draws = 100;
    int classes = 10;
    int vals[classes];
    double probs[4] = {0.1, 0.3, 0.5, 0.1};

    set_seed(123, 456);
    rmultinom(draws, probs, classes, vals);

    for(int j=0; j < classes; j++) {
        printf("Count of class %i drawn: %i\n", j, vals[j]);
    }
    return 0;
}

Count of class 0 drawn: 9
Count of class 1 drawn: 29
Count of class 2 drawn: 49
Count of class 3 drawn: 13
Count of class 4 drawn: 0
Count of class 5 drawn: 0
Count of class 6 drawn: 0
Count of class 7 drawn: 0
Count of class 8 drawn: 0
Count of class 9 drawn: 0

在我的Raku代码中实现raku_rmultinom有问题吗？

**系统信息：**这是在Windows 10 64位中完成的。为了重现性，我在这里提供了头部和动态库：https://replit.com/@sumankhanal/rakunativecall。

要在同一个文件夹中测试带有Rmath. h头和库的C文件，请移动到该目录并从cmd行运行：

gcc -I. -L. <cfile> -lRmath
.\a.exe

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否则，我是这个软件包https://github.com/sumanstats/Statistics的作者，该软件包在全球范围内提供raku_rmultinom，任何人都可以安装和测试输出及其行为。

使用的Raku版本是从https://rakudo.org/dl/rakudo/rakudo-moar-2023.09-01-win-x86_64-msvc.zip;raku -v下载的，提供：

Welcome to Rakudo™ v2023.09.
Implementing the Raku® Programming Language v6.d.
Built on MoarVM version 2023.09.

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