4 ms·
Amusingly, I discovered a method very similar to this in college. My method was simpler - stick a 1 in front of one chemical, then you get an n x n linear syste
by yummyfajitas 11y ago
Amusingly, I discovered a method very similar to this in college. My method was simpler - stick a 1 in front of one chemical, then you get an n x n linear system of equations for the remaining compounds. Solve it, then figure out what to multiply by to get an int solution. I suspect that my version isn't stable, which I gather is the problem these guys are solving.
I was forbidden from using this method on the final, since it isn't the ad-hoc method that was taught.
- eru 11y agoHow are you supposed to solve it, and how would they know?
- wrong_variable 11y agoby placing backdoors in his technique.
- yummyfajitas 11y agoRoughly speaking, this method: http://www.wikihow.com/Balance-Chemical-Equations http://www.wikihow.com/Balance-Chemical-Equations Showing work is required, and if work contains a matrix then they'd just mark it as zero.
- nsajko 11y ago> Showing work is required, and if work contains a matrix then they'd just mark it as zero. Ugh, this makes me so angry and resentful ...
- eru 11y agoLooks isomorphic to what you can do with matrices (including some heuristics to what rows to go for first). Of course, that doesn't make it better.
- nsajko 11y agoDid you ask if it would be alright to use your unusual method and only then had this method disallowed, or did somebody forbid you from using it after eg. seeing you use it for homework? I wonder if they did it purely to reduce the workload of the TAs which will be grading the finals, or did somebody think it would be wrong to have an unorthodox path to the result.
- irixusr 11y agoI was a TA and grading "independent" solutions is a pain. But that's their job. And it's the university's to hire enough TAs to do a good, through, job
- insaneirish 11y agoThis reminds of my first chemistry class in high school. Everything in the beginning seemed so trivial that I tended to not pay attention at all. I had my own methods for various things (including stoichiometry like you). Then the first test came. I seemingly had no problem with it. A few days later, the tests were returned. Everyone got theirs back except for me. I was summoned to the front of the room and the teacher asked me to explain how I did things. We went over the first problem, she understood my explanation. The second, same thing. I was continuing my explanations and she cut me off--"Forget it; I trust you." She flipped the paper over and wrote 100 on it and gave it to me. Boy did that make me never want to do any work in that class again. Apparently I and the eventual valedictorian of our class were real pains in the asses to her. We were "punished" by being given a box of magazines (Scientific American, etc.) and told to sit in the back of the room and not talk. I apologize, Ms. M., for being nuissance, but I think this was a fair treatment rather than being scolded for having my own ways of doing things.
- kwhitefoot 11y agoAnecdotal evidence suggests to me that this is actually all too common. When I describe my primary and secondary schools (1970-1974, Park Senior High, etc., Swindon) where challenging teachers with difficult questions and alternative methods simply prompted the teachers to either gently shoot down your naive idea or return the challenge with something a bit more difficult I am often told "That's how it worked at your school, the rest of us didn't have it so good."