Show HN: Algebra.js – Build, display, and solve algebraic equations

Post by nicolewhite » Fri, Aug 14, 2015, 10:05 PM UTC

dharmatech wrote: post #7

nicolewhite wrote: post #6

Earlier quoted context omitted.

That's very cool. I should definitely add functionality for solving a system of equations.

The algorithm I use in 'EliminateVariables' is pretty ad-hoc and has built up as I throw more situations at it. If you want to look up how the big time guys do it, I believe Mathematica's 'Reduce' performs full on quantifier elimination via cylindrical algebraic decomposition. There aren't many open-source implementations of CAD that I know of besides the venerable C-based QEPCAD. PS: Big fan of your Neo4J tutorials.…

Post by ahmacleod » Fri, Aug 14, 2015, 10:14 PM UTC

Post by heatish » Sat, Aug 15, 2015, 12:17 AM UTC

nicolewhite wrote: post #11

kevin wrote: post #10

This is so well done! There are so many little touches here that delights me like the keyboard shortcuts for jumping right in and the LaTeX support. Even though this started off as a learning project for you, know that this is probably better than 95% of the API documentation I read from more professional development teams. Jason Long's Cayman Theme was unfamiliar to me until I saw your citation. Kudos to your good t…

Thank you for the kind words! I appreciate it. I agree that I should add a bit more instruction for opening up the JS console in Chrome or FF. I'll also add a use case section to show some practical examples. Glad to hear you're interested in RNeo4j; let me know what you think.

  console.log("Type the following in this order pressing enter each time you see a semi-colon: \n var expr = new Expression('x'); \n expr = expr.subtract(3); \n expr = expr.add('x'); \n console.log(expr.toString()); \n var eq = new Equation(expr, 4); \n console.log(eq.toString()); var x = eq.solveFor('x'); \n console.log('x = '' + x.toString());");

Post by nicolewhite » Sat, Aug 15, 2015, 3:03 AM UTC

davmar wrote: post #13

this looks really neat and it must have been a lot of fun to build! it's not a feature request because I don't have a use case for this quite yet, but how complex would it be to parse a string that contains a formula? for example, it seems useful to be able to load equations by just sending the string "2x - 3 = 4" to a function. that sounds like a fun problem to solve as well. maybe useful to the library too. just a…

Post by nicolewhite » Sat, Aug 15, 2015, 3:10 AM UTC

1arity wrote: post #17

the API is really clear and aesthetic. the whole work seems self contained. it is just awesome. im excited to think about an addition for matrices and combinatorics and calculus as well. this deserves to become like a Magma for js. unlike quite a lot of Shown HN this already seems complete, even the documentation, so aside from hoping it expands I feel there isnt much missing to point out. maybe a calculator graphica…