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Cake day: June 6th, 2024

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  • A vector space is when you can:

    • add two Things
    • multiply a Thing by any real number

    And get another Thing that’s the same Kind of Thing.

    By Thing I mean Vector and by Kind of Thing I mean element of the same Vector Space.

    Examples of vector spaces:

    • real numbers
    • complex numbers
    • sets of N numbers (what most people think of when they hear “vector”)
    • matrices
    • polynomials
    • functions
    • quantum states of a given system
    • quantities of apples sold, classified by type of apple

    Examples of Not Vector Spaces:

    • integers
    • negative numbers
    • nonzero numbers
    • unitary matrices
    • apples

    Yeah a few of these come with asterisks I’m happy to answer questions but don’t want to argue with pedants.


  • WolfLink@sh.itjust.workstoTechnology@lemmy.worldSome basic info about USB
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    7 days ago

    Almost everything about it needs to be optional because sometimes USB is used to charge some cheap battery powered thing and sometimes it’s used to make a backup of a harddrive and sometimes it’s charging my laptop with enough power for it to be rendering video but still have a net charge increase to the battery while also providing Ethernet, video output, and keyboard/mouse input over the same one port.

    EDIT to make it more clear why the variability of USB standards is what it is, compare a modern laptop to one from 10 years ago.

    The older laptop has:

    • for video, an HDMI port (or the less common mini HDMI port), and perhaps a mini DP port
    • an Ethernet port
    • a charging plug
    • possibly some FireWire ports (may or may not be the same as the mini DP port)
    • USB A ports for keyboard/mouse and other random devices

    The newer laptop has:

    • USBC ports that can do all of the above

    The perhiperals, however, don’t support all of the features. They only support the features they actually use. As long as the laptop supports all of the optional features, you don’t need to worry about it.

    The is especially helpful for less technical users who may not want to know what the difference between HDMI and DisplayPort is. With a fully USBC based laptop and USBC perhipals you can just plug it in and it will work.

    Of course this is all dependent on the laptop implementing all of the extra features, which is still only really true of more expensive laptops.