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Comment by wruza | Hacker News Reader

I ask to live-design a quadratic equation solving function (the basic method is provided for those who forgot it) and to discuss decisions done. It tests for edge/degenerate case awareness, numeric issues, experience with multiple results specific to a language, and for choosing a prototype that fits the bigger task.

I don’t care if it’s buggy, how much time it takes or whether the first scratch is any good, because it shows fundamental things every decent programmer knows or knows how to discuss and reason about imo. Unlike fizzbuzz, if you pre-solve this question at home and remember these details, you’re already good enough for the next question.

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> I ask to live-design a quadratic equation solving function

I’ve been programming for a decade, was a Linux/cloud engineer a decade before that, I’ve had code on the front page of google, launched products for Microsoft, and had my code shown on stage at nodeconf and aws re:invent. I am currently top 0.07% on stack overflow. I can answer the other questions in this discussion easily. I would absolutely fail this.

Solving quadratic equations is just plugging numbers into the two versions of the quadratic formula.

I can understand forgetting the quadratic formula, but the idea is taught to every school student who takes algebra.

Serious question: why? If I understand OP correctly, it's a 1 line math equation which is provided if necessary and you just need to turn into some useable interface?

I don’t understand. The simple formula is provided, all they’re expected to do is to

- figure out what parameters should look like

- detect edge cases (e.g. division by zero when a==0 or sqrt of negative value)

- and discuss its usage (how to return 0, 1, 2 roots and how you signal it to the caller so it’s convenient)

And this is not a silent-wait quiz. When they seem confused I ask directly what it would return if `a` is zero. Or tell that a, b and c are parameters to such equation.

Anyway, maybe it’s sort of a TIL moment and I should stick more to fizzbuzz with periods changed or to string reversal.

But I feel confused about it as hell.

I dive into math occasionally when working on animation and (real) crypto, and then forget about it when I go back to whatever I'm working on.

Actually looking up the formula for the first time in 20 years it's readable (i.e. doesn't use symbols I don't already know) so yes I'd be able to solve it. That's not guaranteed with every formula though.

Agreed, you can be absolutely horrible at math and be a fantastic programmer. I always found math easy in school but 5+ years later if someone asked me to write a quadratic function solving function I’d have no idea what that even means. Presumably with a guide I could write the code, but that’s so far removed from the type of work I do day to day

Thank you. A lot of the questions in this thread have me seriously doubting myself.

even with the quadratic equation provided?!

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