The matrix/function stuff is elementary enough that I understand it intuitively (I suck at math), although it's neat to be reminded that given a enough independent points you can reconstruct the function (this breaks a variety of bad ciphers, sometimes including ciphers that otherwise look strong).
The kernel post actually does some neat stuff with the kernel, which I found more intuitively accessible than (say) what Strang does with nullspaces.
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Their most recent post about kernels is even better than this:
https://www.dhruvonmath.com/2019/04/04/kernels/
The matrix/function stuff is elementary enough that I understand it intuitively (I suck at math), although it's neat to be reminded that given a enough independent points you can reconstruct the function (this breaks a variety of bad ciphers, sometimes including ciphers that otherwise look strong).
The kernel post actually does some neat stuff with the kernel, which I found more intuitively accessible than (say) what Strang does with nullspaces.