# Persistence factor in 3DEC

**URL:** <https://forum.itascainternational.com/t/persistence-factor-in-3dec/884>\
**Category:** Uncategorized\
**Created:** [January 9, 2023, 9:03pm UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884 "2023-01-09T21:03:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\
**Post date:** [January 9, 2023, 9:03pm UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884/1 "2023-01-09T21:03:54Z")

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Hi, How does 3DEC calculate for persistence? Is it a ratio? I am aware that a value of 1 defines fully persistent while a value of 0.1 or so gives non-persistent joints. But I am curious to know how does the software calculate based the assigned value?

Thanks!  
Vijay

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**Author:** ![Theophile](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/theophile/32/299_2.png) [@Theophile](https://forum.itascainternational.com/u/Theophile)\
**Post date:** [January 10, 2023, 9:47am UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884/2 "2023-01-10T09:47:49Z")

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Hi @VijayKiranKota !

I have no access to the core code, but I’m pretty sure it’s a uniform probability density function.

According to the [documentation](http://docs.itascacg.com/itasca900/3dec/block/doc/manual/block_manual/block_commands/block/cmd_block.cut.html#block.cut):

```auto
persistence f

    Set the probability that any given block lying in the path of a joint will be split
    (i.e., if f = 0.5, then 50% of the blocks will be split, on average).

```

I guess that if another distribution is required (_e.g._, Gaussian), you’ll have to implement it through a Fish function.

Théophile

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**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\
**Post date:** [January 10, 2023, 11:38am UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884/3 "2023-01-10T11:38:15Z")

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Ohh, I see. Got it. Thanks for the prompt response @Théophile.

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**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\
**Post date:** [January 11, 2023, 8:56pm UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884/4 "2023-01-11T20:56:13Z")

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Hi! in 3DEC the persistence set the probability that any given block lying in the path of a joint will be split (i.e., if f = 0.5, then 50% of the blocks will be split, on average)

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**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\
**Post date:** [January 13, 2023, 11:49am UTC](https://forum.itascainternational.com/t/persistence-factor-in-3dec/884/5 "2023-01-13T11:49:26Z")

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Got it. Thanks for your reply @msepu.  
Vijay