Andy Ruina

Mechanical Engineering guy

[Andy Ruina @andyruina]

@GwenWalz @BarackObama Buttons at least.

[Andy Ruina @andyruina]

@stevenstrogatz Like, where is the 2 pi in those curves spaced with 1/e?

[Andy Ruina @andyruina]

@stevenstrogatz _add_ them up

[Andy Ruina @andyruina]

@stevenstrogatz Expanding a bit on my question above. Take a group of 4 of those terms and multiply by 1,0, -1, 0. Then add up successive groups of 4. And you get a periodic function, a sine or cosine, that has a period that is incommensurate with the "period" of the group of 4. Seems odd.

[Andy Ruina @andyruina]

@Quasilocal Fun puzzle. In the end, nothing tricky about it. It all falls into place. Don't forget "karaoke".

[Andy Ruina @andyruina]

@stevenstrogatz For the Dave Block book Steve Strogatz links to above, the link seems broken somehow. Go to this course link and click on the fifth resource: https://t.co/OVQx0TMEuz

[Andy Ruina @andyruina]

@Turb1neG1rl @BidensWins @FrankMikeDavis1 20 tons would be a lot for on truck. 20 trucks would be 400,000 kg. For 2,000,000 people that’s 200 grams/person. If it is all oil and fat, at 9 Cal/gram that would make enough food for one day. But the trucks are probably not that big and it’s probably not all fat.

[Andy Ruina @andyruina]

@JohanSalomon @stevenstrogatz I am not a chess player. My solution is Queen to f5 then rook to f6. It's a puzzle but what is so great about it?

[Andy Ruina @andyruina]

@BCiechanowski This concept, of making every drawing a user-controlled animation, is great. Added on to your clear explanations, you are doing an educational service to the world.

[Andy Ruina @andyruina]

@stevenstrogatz Totally engaging. An hour long movie would be great, even if it becomes mostly technical.

[Andy Ruina @andyruina]

@dr_annek Croatia South of Trieste?

[Andy Ruina @andyruina]

@stevenstrogatz With Im(sqrt(z)) you don't have a function of two variables because the Rieman surface has two sheets. It's somehow clarifying, maybe, to think of the domain in polar coordinates with 0<= theta< 4 pi. For that domain you get a nice function of r,theta (w r>0).

[Andy Ruina @andyruina]

@AlcockNews @AmericanAir @boomsupersonic Expected passenger miles per gallon (or liters per 100 passenger km, or whatever)?

[Andy Ruina @andyruina]

@StevenHCollins Never heard of him or his books. Looked him up. Charming guy in the 4 interviews/videos I saw.

[Andy Ruina @andyruina]

@stevenstrogatz Unseen #s of Twitter followers smarm on the internet to watch the swarms of people watching the swarms of bats each made of a swarm of cells.

[Andy Ruina @andyruina]

@10kdiver And how do you figure out how many digits are in the password?

[Andy Ruina @andyruina]

@10kdiver It was too close to one of your division boundaries to do in my head. So I had to actually calculate. Annoying.

[Andy Ruina @andyruina]

@stevenstrogatz 2 thoughts. 1) This is a bit like the debate about the value of 1/2+2, it’s a matter of definition; 2) zero is also problematic (0•1=0•2=>1=2) and needs special treatment (although not quite as much), why is the question about infinity so different than the discussion about 0?

[Andy Ruina @andyruina]

@rd_wilkinson @biomechAnthony @rosshm16 No.