Laundry list of little mathmo question problems

[alexwlchan]

I’ll be out of Cambridge for the next few days, and only making sporadic fixes. I’m making this list for personal reference, but having it here might be useful too.

• In complex arithmetic, occasionally it spits out a horrible decimal. Example
• In modulus argument, sometimes answers come in the form $6e^0$. This feels overly simple or trivial; I think we should probably deliberately escape this case. Example
• In rank 2 and rank 3 matrices, it might be nice to pull common fractions outside the matrix. e.g. $$\frac{1}{17}\begin{pmatrix}1 & 2 \ 3 & 4\end{pmatrix}$$ as opposed to $$\begin{pmatrix}\frac{1}{17} & \frac{2}{17} \ \frac{3}{17} & \frac{4}{17}\end{pmatrix}.$$ Not sure how easy it would be to implement.
• I have a typo to fix in further vectors.
• I can do some more tidying in Newton-Raphson to make the decimal points line up.
• Formatting of $dx$ in integration by substitution. Also spacing in the denominator.
• Spacing in figures of revolution.
• In differential equations, if the term on the RHS is negative, then pull it over so the RHS is zero. Example
• In 2nd order DEs, investigate adding forcing terms on the RHS (this is a common problem at A-level).
• In stationary points, write a full sentence for the answer.
• In implicit differentiation, correct the formatting of $\frac{dy}{dx}$ and some wording.
• In vector equations, fix a typo that I made.

List here to account for the stack of commits I’ll push over the next few days, but also for other people to contribute to. Put other small fixes or minor issues with Mathmo in this thread, and I’ll work my way through the list over the next few days.

[alexwlchan]

There’s a coefficient of +1y here: http://nrich.maths.org/mathmoApp/#/mathmo/Alex/C33/1007 and is should just be +1y.

Also this one is a bit off: http://nrich.maths.org/mathmoApp/#/mathmo/Alex/C33/1023

[gmp26]

We need to fix the routing. None of these shared URLs are working.

M

On 11 Jul 2013, at 17:28, Alex Chan wrote:

There’s a coefficient of +1y here: http://nrich.maths.org/mathmoApp/#/mathmo/Alex/C33/1007 and is should just be +1y.

Also this one is a bit off: http://nrich.maths.org/mathmoApp/#/mathmo/Alex/C33/1023

— Reply to this email directly or view it on GitHub.

Mike Pearson +44 (0)1223 764244 +44 (0)7742 6418207 MMP, Centre for Mathematical Sciences, Cambridge CB3 0WA

[alexwlchan]

• Implicit differentiation is fixed in 53c2904
• Vector equations (makeFurtherVector) is fixed in 551c0b0
• Typo in integration by substitution is fixed in 3cf666c
• Problems in my second comment (par/perp equations) fixed in 8cb6f28

[alexwlchan]

Add unit tests to account for the edge cases in parallel/perpendicular line equations.

[alexwlchan]

• The stray comma in makeVectorEq is fixed in e8be24c
• The formatting of differential equations is fixed in 85aeab3

[alexwlchan]

• Matrices are fixed in 4bdafa0
• Spacing in figures of revolution is fixed in 0b317e4
• Stationary points are fixed in 866235d

[gmp26]

Thankyou!

M

On 15 Jul 2013, at 15:19, Alex Chan wrote:

• Matrices are fixed in 4bdafa0 • Spacing in figures of revolution is fixed in 0b317e4 • Stationary points are fixed in 866235d — Reply to this email directly or view it on GitHub.

Mike Pearson +44 (0)1223 764244 +44 (0)7742 6418207 MMP, Centre for Mathematical Sciences, Cambridge CB3 0WA

[alexwlchan]

Of the points discussed above, these remain:

• In complex arithmetic, occasionally it spits out a horrible decimal.
• In 2nd order DEs, investigate adding forcing terms on the RHS (this is a common problem at A-level).

In addition, I’ve found some more items:

• What’s gerwrite() doing in polys.ls? It’s commented out at the moment, so right now, not a lot.
• Add tests for the probability mass functions in stats.ls
• Tidy up the LaTeX and HTML for the tables in stats.ls
• Write the complex gcd in complex.ls
• Find a better way to do Newton-Raphson
• Finish debugging makeChiSquare

Most of the qa files are now in LiveScript, which I’ve been doing as I integrate them into CMEP. I’ve not pushed them yet, because I still need to work out a few bugs (related to the fact that LS doesn’t have the ternary operator).

[gmp26]

Spewing out nasty decimals is usually best solved by appealing to Number.toPrecision or Number.toFixed. These return strings so are safe. LS ternary operator is 'if x then a else b' rather than the usual 'x ? a : b'. Not sure why they chose to be more verbose than js there. No idea about gerwrite().

[alexwlchan]

I think the decimals should be fractions, so I need a peek to see why the frac object is turning into a decimal. I’m not sure if Number.toPrecision or Number.toFixed would be useful here.

Yep. I’m doing a few workarounds, and I suppose their ternary is more LiveScript-like. Hmm.

shrug It’s still in there, commented out, so we can get it out if needs be.

[alexwlchan]

A few more:

• Spacing in makeTriangle
• Use <li> for makeCircle
• Full stops
• MathJax in makeDETwoHard