[Tutor] Help with Recurring Function

[Kent Johnson]

Sanhita Mallick wrote:

> I am struggling with a simple recurring function

What is a recurring function? Do you mean looping?
> 
> Here is the script. T(i) are trees (as in graphs).
> The program operates great, until the step where
> norm_ted is calculated. Mysteriously norm_ted becomes
> 0, even though "mag" value is calculated correctly.
> Also, strangely, sum_norm_ted also becomes zero. 
> 
> What am I missing?

Do you mean for sum_norm_ted to be the sum over all i and j? If so, you 
should initialize it before the start of the outer loop.

I don't know why you are getting 0 at the end of the loop. It is as if 
sum_norm_ted and norm_ted are initialized but the inner loop doesn't 
run. Is this the exact code that you have trouble with?

Kent
> 
> Thanks.
> -Sanhita
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> T = [F1, F2, F3]
> k = len(T)
> mean_ted = {}
> for i in range(k):    
>     sum_norm_ted = 0.0
>     mag = 0.0
>     norm_ted = 0.0
>     for j in range(k):
>         if (i != j):
>             ted= alg.ted(T[i], T[j])
>             print 'TED ' + str(i) + str(j) + ' is ' +
> str(ted)
>             mag = 2 * (T[i].n + T[j].n) - 1
>             print 'MAG ' + str(i) + str(j) + ' is ' +
> str (mag) + ' and ' + str ( 2 * ted )
>             norm_ted = (2 * ted) / mag 
>             print 'norm_ted ' + str(i) + str(j) + ' is
> ' + str (norm_ted)
>             sum_norm_ted = sum_norm_ted + norm_ted
>             print 'sum_norm_ted ' + str(i) + str(j) +
> ' is ' + str (sum_norm_ted)
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