Accessing variable from a function within a function

James Stroud jstroud at mbi.ucla.edu
Sun Jun 24 21:41:45 CEST 2007


James Stroud wrote:
> Nathan Harmston wrote:
> def exteuclid(m,n):
>  x = 0,1,1,0,m,n
>  def euclid(c,d,x=x):
>        a,a1,b,b1,c,d = x
>        q = c /d
>        r = c % d
>        if r == 0:
>            print a,b
>            return d
>        else:
>            print a1,a,b1,b,c,d,q,r
>            t = b1
>            b = t - q * b
>            a = t - q * a
>            c,d,a1,b1 = d,r,a,b
>            return euclid(c,d)
>        return euclid(c,d)
> 
> James

My answer above is wrong because c and d take the wrong default values. 
Also, you have some ambiguity in your code. Are nested calls to euclid 
supposed to have the original values of a, a1, b, & b1, or are they to 
take the original values 0, 1, 1, 0? This type of ambiguity is one 
reason why the interpreter does not like reference before assignment. 
This is my best guess at what you want because I'm not familiar with how 
euclid's algorithm works:

def exteuclid(m,n):
   def euclid(a,a1,b,b1,c,d):
        q = c /d
        r = c % d
        if r == 0:
            print a,b
            return d
        else:
            print a1,a,b1,b,c,d,q,r
            t = b1
            b = t - q * b
            a = t - q * a
            c,d,a1,b1 = d,r,a,b
            return euclid(a,a1,b,b1,c,d)
   return euclid(0,1,1,0,m,n)



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