reddit is a platform for internet communities

where your votes shape what the world is talking about.

learn more ›

What's your mother's signature dish? by spunkyass69in AskReddit

[–]MadPat 0 points1 point  (0 children)

Rigatoni and meat balls.

My mother was an Irish lady who was a great cook. But we lived in an Italian neighborhood and she hung around with the Italian women and learned all of there secrets. She made terrific spaghetti sauce that would take a day to cook slowly simmering on the top of the stove. JUST THINKING OF THE SMELL IS NOW DRIVING ME CRAZY!!!!

Mom's been gone for a long time now but I still remember those feasts.

[Linear Algebra] System of linear equations by terroh8erin learnmath

[–]MadPat 1 point2 points  (0 children)

From 1, you get b=c as you mentioned. But then (4) becomes 4d = 4d which says nothing so forget about it.

This leaves you with (2) which is now 3a +2b-3d = 0 and (3) 3a+2c-3d = 0. Since b=c these are the same.

So, it comes down to:

3a+2b-3d = 0 and b = c.

From the first, you can get b in terms of a and d and then c follows from that.

So, pick practically any a and d, say 4 and 8, then you get c and b. That is the point behind this.

By the way, if you pick a=d, then you get a diagonal matrix which does commute.

Why is matrix multiplication the way that it is? by coaster367in math

[–]MadPat 0 points1 point  (0 children)

Suppose you have the system of equations:

a*x1+b*x2 = p

c*x1+d*c2 = q

where p and q are known.

In matrix terms this is:

[ a b ][ x1 ] = [ p ]

[ c d ][ x2 ] = [ q ]

Suppose you also have:

r*y1+s*y2 = x1

t*y1+u*y2 = x2

In matrix terms this is:

[ r s ][ y1 ] = [ x1 ]

[ t u ][ y2 ] = [ x2 ]

Substitute the second set of equations into the first set to get equations to solve for y1 and y2 knowing p and q.

Formulate this last set of equations in matrix terms. What does this last matrix have to do with the first two matrices?

I hope you can deal with the formatting.

Math & Baseball fans: What are the odds of a team getting 9 consecutive hits without recording an out? by KarDal0in math

[–]MadPat 2 points3 points  (0 children)

You would need to know all of the players true batting averages against David Price to find out that probability. I doubt there is enough data to get that.

However, as an estimate, you could just multiply their averages.

Here is a starting lineup I found at ESPN:

  1. Brett Gardner .269
  2. Derek Jeter .267
  3. Jacoby Ellsbury .285
  4. Mark Teixeira .230
  5. Brian McCann .238
  6. Yangervis Solarte .254
  7. Ichiro Suzuki .289
  8. Brian Roberts .237
  9. Brendan Ryan .213

Multiply them together and we get


Murderer's row, they ain't.

Research in linear algebra? by letoseldonin math

[–]MadPat 0 points1 point  (0 children)

Look into statistics, too. The "general linear model" is really applications of linear algebra to problems with lots of data.

Teachers or professors of Reddit, what is the most elaborate cheating scheme you've stumbled upon? by jerip123in AskReddit

[–]MadPat 1 point2 points  (0 children)

OK. Big Calc exam. Many different sections. All instructors present in the same large lecture hall.

One particular person, call him Z, is just sort of sitting there doing nothing looking around. Professor A begins to stare hard at him hoping to get him to stop rubber necking. Eventually Z stops looking around and begins to write in his exam book.

Exam comes to the end and Z walks down to hand in his paper. Professor A takes it and notices there is no name on it. A asks Z to sign his name. Z does and leaves the room.

A turns to Professor B and says "Hmm. I had to make that guy sign his name." Professor B looks at the paper and says, "Well, he is in my class but that is not his name." (Z has signed X's name to the paper.) Now A and B look at Professor C, point to the paper and ask, "Is this guy in your section?" C looks at the name on the paper they have and says "But I have X's paper right here." and pulls out a completed exam.

So now they have Z who has signed X's name to a paper but the real X has also handed in an exam.

Next day, Professor B goes into the office and finds an exam slipped under his door. It has Z's name on it and it is mostly correct and complete. There is a note attached to it: "We found this paper in the big classroom after your exam yesterday. Signed: custodial staff."

B contacts the custodial staff and they know nothing of this.

B just flunks Z and never hears anything more.

What is the strangest "wrong number" call you've gotten? by kiwidaffodil19in AskReddit

[–]MadPat 11 points12 points  (0 children)

I had just been checked into the hospital and I was quite ill. (Cellulitis. Temperature well over 100. Very groggy. I had an IV and felt terrible and very weak.)

The phone in the room rang.

I picked it up and a man asked me to put on someone with a woman's name. (I was in a single room. )

Me: There's nobody here by that name.

Him: Well did she check out.

Me: I don't know.

Him: Transfer me to her.

Me: I am a patient. I don't know how to do that.

Him: (Irritably) Well ask somebody.

Me: I'm a patient. I'm waiting for my doctor.

Him: Well, transfer me to the switchboard.

Me: I can't do that. I'm a patient.

Him: Why not?


Then I was in such a weakened condition that I began crying.

Him: Swore and hung up.

Strangest call I ever dealt with.

The Legend of John von Neumann by baialeph1in math

[–]MadPat 0 points1 point  (0 children)

There is better formatting in the PDF here.

[University Probability] Product Sets and Combinations Problem? by amazinglyanonymousin learnmath

[–]MadPat 1 point2 points  (0 children)

Think about a set with 7 elements that can either be heads or tails. In order to get three heads, you need to pick a subset of three elements and make them heads. Once you have that, make the rest of the set tails.

How many different sets of three elements are there? C(7,3). That's where they get the numerator.

Should I get a kindle Paperwhite, or an Android tablet? by mirbiusin kindle

[–]MadPat 0 points1 point  (0 children)

I just use acrobat reader. As far as I know, I can not synchronize the tablet fiels with the windows files.


[–]MadPat 0 points1 point  (0 children)

See my comment above. I have a lot of scientific stuff, too. I just copy it over to a mini SD card and put it into the android.


[–]MadPat 0 points1 point  (0 children)

I can tell right now I am going to be a voice crying in the wilderness.

I have an android tablet and I would not trade it for all of the kindle hardware. I have both kindle and nook apps on it as well as both the Oyster and Scribd rental services. (I really, really, really like to read dontcha know.)

I can also get e-mail and other stuff on it but, I use it mostly for just reading. I have YouTube and Netflix but I don't use them much at all.

Give me my Android or give me boredom!!!!

So this asshat thinks he has something to say about Rhode Island. I say we tell him what we think about his article. by EllisDee3in RhodeIsland

[–]MadPat 2 points3 points  (0 children)

I think this is satire although not particularly funny. It's just too heavy-handed.

As proof of a satirical bent, this is the biography of one of their "Journalists".


Furthermore, if you look at the comments on the articles, you see that a lot of them are from the same people who are supposed to be reporters.

When and How Did You First Discover You Had a Fetish? [NSFW] by SaintOdhranin AskReddit

[–]MadPat -3 points-2 points  (0 children)

My fetish is gossip and I can't wait until I can tell people some of these things.

generic complaint by atsjzvin math

[–]MadPat -1 points0 points  (0 children)

Your complaint is well-taken. It is one of the points behind A Mathematician's Apology by G. H. Hardy and, to a lesser extent The Two Cultures by C. P. Snow. (Snow enlarged the argument to apply it to all of science vis-a-vis non-science.)

It has always been one of my gripes. When I was teaching, nobody ever asked me about my research in abstract algebra. They were delighted to speak with me when they needed help with a computer, however. Then, I was a good resource. (Yeah.... Just like the janitor....)

Math you have a soft spot for by foxjwillin math

[–]MadPat 0 points1 point  (0 children)

One mildly interesting corollary of the idea of putting the mean back into the set is that the variance estimator no shrinks by a factor of (n-1)/n.

Has anyone read "What is Mathematics" by Courant and Robbins? by oilerequationin math

[–]MadPat 0 points1 point  (0 children)

It is a good book. You should read it if only for the fact that it has a nice way to trisect the angle using a ruler as a measuring device. (This is usually not taught in grad school.)

looking for scenery in Rhode island to get good video by Qnzkrewin RhodeIsland

[–]MadPat 0 points1 point  (0 children)

Wait until the fall colors are out and then fly down route 6 by the Scituate reservoir. No guarantees but I think that would look great.

Lots of places in Rhody look nicer when the colors are out.

Motivation for the Group Theory Axioms by jakob1111in math

[–]MadPat 0 points1 point  (0 children)

I don't know of anybody who has written an abstract algebra book with this as an underlying theme. I just thought it was a good idea and I would do it if I ever have a chance to teach abstract algebra again. This is extremely unlikely since I am now retired.

Obama blasts US firms for 'magically becoming Irish' in controversial tax switches by psychonautistin worldnews

[–]MadPat -2 points-1 points  (0 children)

The US did that in 2005. We declared a "Repatriation Tax Holiday" because it would work wonders for us. We would all have more money and the sun would shine brighter and birds would sing sweeter songs.

THAT'S GREAT!! Except for the fact that the companies that repatriated their money spent the money on stock buybacks and executive compensation.

And, oh yeah, the fact that the top fifteen repatriators cut about 21000 net jobs didn't help either.

Motivation for the Group Theory Axioms by jakob1111in math

[–]MadPat 7 points8 points  (0 children)

Actually, if I were going to motivate group theory to a bunch of undergraduates, I would point out that a group is the smallest mathematical system in which you can solve the equation a*x = b.

You need all of those axioms to do this.

Then I would point out that, once we have these axioms in place, we can also look at permutation groups, matrix groups, etc.

I know that permutation groups were the first groups used; I just think the above is a better way to motivate for undergraduates without any knowledge of permutations.

Toposes, Triples and Theories, by Michael Barr And Charles Wells [.pdf] by nastratinin math

[–]MadPat 1 point2 points  (0 children)

Oh, I dunno. The original concept of triple comes from a paper by Eilenberg and Moore that you can find here. Triples were then explored more fully by Jonathan Beck in his Thesis which was very important but never really was published. Instead he and Barr laid out the basics of the theory in several papers. MacLane disliked the name for his own reasons with which I do not agree. I never had any needless confusion; sorry if he did.

By the way, if you want to find a lot of reprints of worthwhile early articles on category theory, go here.

Worst Typo Ever On My College Diploma by AHarrisJDMBAin funny

[–]MadPat 1 point2 points  (0 children)

Well, another state has done something sorta like that. It even appeared on the diploma in 1988. That was the year I graduated and I desperately wanted one; unluckily mine was spelled correctly.