Same person as @[email protected], different instance.

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Joined 2 years ago
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Cake day: April 3rd, 2024

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  • The CSR (compressed sparse row) format is a very simple but efficient way of storing sparse matrices, meaning matrices with a large amount of zero entries, which should not all occupy memory. It has three arrays: one holds all non-zero entries in order, read row by row, the next array contains the column indices of each non-zero element (and therefore has the same length as the first array), the third array indices into the first array for the first element of each row, so we can tell where a new row starts.

    On sparse matrices it has optimal memory efficiency and fast lookups, the main downside is that adding or removing elements from the matrix requires shifting all three arrays, so it is mostly useful for immutable data.






  • The practical answer is: you drive as far as you legally can.

    As a disclaimer, pictured here are the Himalayas, which are at a completely different scale to where I’ve been, but in my experience there are typically parking spaces/bus stops at the end of public roads. At this point you leave the built up infrastructure and enter nature, and these are often located in a place where the flatter valley ends and a steeper ascent begins. In many cases there are smaller private roads further up to service more remote cabins or farmsteads. Sometimes there are even taxi services that drive you further along using private roads, which can be seen as not fully scaling the mountain yourself. Generally, the closest public parking is considered the starting point and most people will therefore start at the same spot.