Comment on Explain yourselves, comp sci.

SpaceNoodle@lemmy.world ⁨11⁩ ⁨months⁩ ago

• fossilesque@mander.xyz ⁨11⁩ ⁨months⁩ ago

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  • ipha@lemm.ee ⁨11⁩ ⁨months⁩ ago

    It’s like a fancy list.

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    • fossilesque@mander.xyz ⁨11⁩ ⁨months⁩ ago

      So is a wedding gift registry.

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      • whereBeWaldo@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

        No this is Patrick!

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  • Fosheze@lemmy.world ⁨11⁩ ⁨months⁩ ago

    It’s a dynamically-sized list of objects of the same type stored contiguously in memory.

    dynamically-sized: The size of it can change as needed.

    list: It stores multiple things together.

    object: A bit of programmer defined data with.

    of the same type: all the objects in the list are the same kind of object

    stored contigiously in memory: if you think of memory as a bookshelf then all the objects on the list would be stored right next to each other on the bookshelf rather than spread across the bookshelf.

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    • kbotc@lemmy.world ⁨11⁩ ⁨months⁩ ago

      Dynamically sized but stored contiguously makes the systems performance engineer in me weep. If the lists get big, the kernel is going to do so much churn.

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      • Killing_Spark@feddit.de ⁨11⁩ ⁨months⁩ ago

        Contiguous storage is very fast in terms of iteration though often offsetting the cost of allocation

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      • IAmVeraGoodAtThis@lemmy.blahaj.zone ⁨11⁩ ⁨months⁩ ago

        Which is why you should:

        1. Preallocate the vector if you can guesstimate the size
        2. Use a vector library that won’t reallocate the entire vector on every single addition (like Rust, whose Vec doubles in size every time it runs out of space)

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      • yetiftw@lemmy.world ⁨11⁩ ⁨months⁩ ago

        matlab likes to pick the smallest available spot in memory to store a list, so for loops that increase the size of a matrix it’s recommended to preallocate the space using a matrix full of zeros!

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      • tamal3@lemmy.world ⁨11⁩ ⁨months⁩ ago

        Is that churn or chum? (RN or M)

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  • SpaceNoodle@lemmy.world ⁨11⁩ ⁨months⁩ ago

    Many things like each other lined up in a row, and you can take some away or put more in.

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  • mindbleach@sh.itjust.works ⁨11⁩ ⁨months⁩ ago

    It’s how you want an array to work.

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• Leate_Wonceslace@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

  No, it’s an n-tuple with certain algebraic properties.

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  • KidnappedByKitties@lemm.ee ⁨11⁩ ⁨months⁩ ago

    This is such an understated but useful description in this context. It’s also how I understood algebra for applied matrix computation.

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    • Leate_Wonceslace@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

      I was just coming down from THC when I wrote this, so I’m extra jazzed you liked it. 😁

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  • GnomeKat@lemmy.blahaj.zone ⁨11⁩ ⁨months⁩ ago

    Its the algebraic properties that are important, not all vectors are n-tuples, eg the set of polynomials of degree less than n.

    You need a basis to coordinate a vector, you can work with vectors without doing that and just deal with the algebraic properties. The coordinate representation is dependent on the basis chosen and isn’t fundamental to the vector. So calling them n-tuples isn’t technically correct.

    You can turn them into a set of coordinates if you have a basis, but the fact that you can do that is because of the algebraic properties so it’s those properties which define what a vector is.

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    • Leate_Wonceslace@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

      I think a better example to show how vectors don’t necessarily need to be what people conceptualize as n-tuples would have been the real numbers. (Of course, these can be considered 1-tuples, but the same can be said of any arbitrary set element that is not itself a tuple with more entries.) A cooler example would have been R[x] (the ring of real-valued polynomials of a single variable) especially since an isomorphic ring using n-tuples would be a more cumbersome representation of the algebra.

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• conquer4@lemmy.world ⁨11⁩ ⁨months⁩ ago

  So an ArrayList?

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  • joyjoy@lemm.ee ⁨11⁩ ⁨months⁩ ago

    No. ArrayList is thread safe and implements the connections API. Vector doesn’t. Though if you’re using Java, there’s almost no instance where you would want to use a Vector instead of ArrayList.

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    • DaPorkchop_@lemmy.ml ⁨11⁩ ⁨months⁩ ago

      ArrayList isn’t thread-safe, though…

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      • joyjoy@lemm.ee ⁨11⁩ ⁨months⁩ ago

        Thread safe as in it raises an exception instead of breaking your list.

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