Question

我对Groovy很新。我正在用它的属性来解决斐波那契数列。我有一个像这样的groovy代码：

a = new BigInteger[2][2]
a[0][0] = 1
a[0][1] = 1
a[1][0] = 1
a[1][1] = 0
temp = new BigInteger[2][2]
temp = a
def testFun(def a,BigInteger n) {
    if(n == 1)
        return a
    b = new BigInteger[2][2]
    def sum = 0
    for ( c = 0 ; c < 2 ; c++) {
                for ( d = 0 ; d < 2 ; d++ )
                {   
                   for ( k = 0 ; k < 2 ; k++ )
                   {
                      sum = sum + temp[c][k] * a[k][d];
                   }
           b[c][d] = sum
               sum = 0;
            }
         }
        testFun(b,n-1)
}
c = new BigInteger[2][2]
BigInteger n = 90
if( n % 2 == 0 )
{   
        c =  testFun(a,n.divide(2))
        temp = c
        c = testFun(c,2)
}
println c[0][1]

我得到的答案如下：

2880067194370816120

但是，当我将n值更改为5090时，我会收到如下错误：

at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)
    at fibb.testFun(fibb.groovy:24)
    at fibb$testFun.callCurrent(Unknown Source)

出了什么问题？为什么我收到此错误？

Answer 1

虽然我原本希望在该堆栈跟踪中看到StackOverflowException，但也许你只是将其剪掉了。我认为你正在遇到最大的递归深度，这就是为什么它适用于n的小值，但是失败的值很大。你想看看关闭trampolining，Groovy 1.8的一部分。以下是release notes的相关部分。

还有this question类似，应该可以帮到你。

顺便说一下，它在堆栈跟踪中显示“Unknown Source”的原因是因为Groovy没有可用的源来告诉你它在哪一行 - 它是一个红色的鲱鱼。

这个未知来源错误是什么意思？

1 个答案: