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Today's Topics:
1. Re: list doesn't end (Alexander Chen)
2. Re: list doesn't end (Francesco Ariis)
3. Re: list doesn't end (Alexander Chen)
----------------------------------------------------------------------
Message: 1
Date: Sun, 24 Nov 2019 17:10:17 +0100 (CET)
From: Alexander Chen <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] list doesn't end
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi Francesco,
length a2 = 7072
length b3 = 7072
length c4 = 82
I suspect its the first two that get it into trouble. Is is 7072*7072*82 =
41014081088 permutations, 100*3 = 1000000.
So I am guessing that this is not the fix to the euler problem....
best.
November 23, 2019 8:05:32 PM CET Francesco Ariis <[email protected]> wrote:Hello
Alexander,
On Sat, Nov 23, 2019 at 07:38:03PM +0100, Alexander Chen wrote:
> Hi,
>
> I am doing some further learning with euler now in Haskell instead of Julia.
But I am getting something strange.
>
> [x+y+z | x <- a2, y <- b3, z <- c4, (x+y+z) < 50]
>
> a2, b3, c4 are all finite lists derived from the lazy list of the primes
package. the output is:
>
> [28,47,33,49
λ> :m Data.Numbers.Primes
λ> let a = take 100 primes
λ> length [x+y+x | x <- a, y <- a, z <- a, (x+y+z) < 50]
942
I suspect one in [a2, b3, c4] is infinite (or very very long). Can you
paste the whole calculation?
-F
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Message: 2
Date: Sun, 24 Nov 2019 19:19:51 +0100
From: Francesco Ariis <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] list doesn't end
Message-ID: <[email protected]>
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On Sun, Nov 24, 2019 at 05:10:17PM +0100, Alexander Chen wrote:
> Hi Francesco,
>
> length a2 = 7072
> length b3 = 7072
> length c4 = 82
>
> I suspect its the first two that get it into trouble. Is is 7072*7072*82 =
> 41014081088 permutations, 100*3 = 1000000.
>
> So I am guessing that this is not the fix to the euler problem....
If `x+y+z` need to be <50, and the three are primes, I am puzzled to see
such lengths!
Which problem is it?
------------------------------
Message: 3
Date: Mon, 25 Nov 2019 08:55:17 +0100 (CET)
From: Alexander Chen <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] list doesn't end
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi Francesco,
Their is a ^2, ^3, ^4 in the lists, respectively.
see https://projecteuler.net/problem=87
best,
November 24, 2019 7:19:51 PM CET Francesco Ariis <[email protected]> wrote:On Sun,
Nov 24, 2019 at 05:10:17PM +0100, Alexander Chen wrote:
> Hi Francesco,
>
> length a2 = 7072
> length b3 = 7072
> length c4 = 82
>
> I suspect its the first two that get it into trouble. Is is 7072*7072*82 =
41014081088 permutations, 100*3 = 1000000.
>
> So I am guessing that this is not the fix to the euler problem....
If `x+y+z` need to be <50, and the three are primes, I am puzzled to see
such lengths!
Which problem is it?
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