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Using piecewise-defined functions for recursive integer sequence

asked 2019-12-30 16:46:55 +0200

geroyx gravatar image

I have

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with div --> // ("integer part" of division).

I wonder how to use piecewise-defined functions for calculating n(i) and Q(i).
This does not work:

r = 1
m = 7
n(i) = piecewise([([0,0], r//m), ((0,oo), 10*(n(i-1)-Q(i-1)*m))])
Q(i) = piecewise([([0,0], 0), ((1,oo), n(i)//m)])

print n(0)
print n(1)
print n(5)

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answered 2019-12-31 09:49:06 +0200

Jingenbl gravatar image

r = 10

m = 2

def fonction_n(k):

if k == 0:

    return r//m

return 10 * (fonction_n(k-1) -  fonction_q(k-1) * m)

def fonction_q(k):

if k == 0:

    return 0

return fonction_n(k)//m

It is possible to derecursify this functions

happy new year

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With def ....: if... it is clear. I ask myself: Is there a way with piecewise.

geroyx gravatar imagegeroyx ( 2019-12-31 14:46:09 +0200 )edit

it is not a sagemath problem but an interesting mathematical question, right?

I write two or three equations, just to see if the answer is within pen's reach

Jingenbl gravatar imageJingenbl ( 2020-01-01 09:48:08 +0200 )edit

define F(x)=10(x%n)

so n(k)=F(F(F....(F(r//m)...) with k iterations.

What do you mean by a piecewise function , when the function is defined for three variables k, r and m ?

happy new year

Jingenbl gravatar imageJingenbl ( 2020-01-01 10:20:30 +0200 )edit

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Asked: 2019-12-30 16:46:55 +0200

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Last updated: Dec 31 '19