• linearchaos@lemmy.world
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    1 month ago

    I could never remember the formula to calculate compound interest.

    But I had no trouble writing a for loop.

      • linearchaos@lemmy.world
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        1 month ago

        I would just rebuild something in my head like this every time.

        While i < n; k=k+(k*r); i++;

        You’d think I could remember k(1+r)^n but when you posted, it looked as alien as it felt decades ago.

        • VintageGenious@sh.itjust.works
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          1 month ago

          The use of for makes sense.

          k=0; for (i=0; i<n; i++) k=k+f(i); is the same as k=\sum_{i=0}^{n-1} f(i)

          and

          k=1; for (i=0; i<n; i++) k=k*f(i); is the same as k=\prod_{i=0}^{n-1} f(i)

          In our case, f(i)=1+r and k=1; for (i=0; i<n; i++) k*(1+r); is the same as k=\prod_{i=0}^{n-1} (1+r) = (1+r)^n

          All of that just to say that exponentiation is an iteration of multiplication, the same way that multiplication is an iteration of addition

    • BluesF@lemmy.world
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      1 month ago

      What always annoyed me was having to draw charts by hand. Just let me put the data in a computer for god’s sake, the rest of the working is there… I did actually write a python function for one of my assignments which was fine, but they told me not to do it for the exam.