将ruby数组值传递到C数组中

我已经注意到几种在ruby和c之间传递不同值的方法.然而,对于ruby和C来说,它都是相当新的,并且无法解决如何将数组从VALUE ruby??对象复制到C数组中的问题.

编译错误：
SimpleFFT.c：47：错误：下标值既不是数组也不是指针

和代码：

#include "ruby.h"
#include "fft.c" // the c file I wish to wrap in ruby

VALUE SimpleFFT = Qnil;
void Init_simplefft();
VALUE method_rfft(VALUE self,VALUE anObject);

void Init_simplefft() {
    SimpleFFT = rb_define_module("SimpleFFT");
    rb_define_method(SimpleFFT,"rfft",method_rfft,1);
}

VALUE method_rfft(VALUE self,VALUE inputArr) {
    int N = RARRAY_LEN(inputArr); // this works :)

    // the FFT function takes an array of real and imaginary paired values
    double (*x)[2] = malloc(2 * N * sizeof(double)); 
    // and requires as an argument another such array (empty) for the transformed output
    double (*X)[2] = malloc(2 * N * sizeof(double));

    for(i=0; i<N; i++) {
        x[i][0]=NUM2DBL(inputArr[i]); // ***THIS LINE CAUSES THE ERROR***
        x[i][1]=0;  // setting all the imaginary values to zero for simplicity
    }

    fft(N,x,X); // the target function call

    // this bit should work in principle,dunno if it's optimal
    VALUE outputArr = rb_ary_new();
    for(i=0; i<N; i++){
        rb_ary_push(outputArr,DBL2NUM(X[i][0]));
    }

    free(x);
    free(X);

    return outputArr;
}

提前致谢 ：)