Home again, 2/11/15

I should've gotten home quicker than this, but that last one, I wasn't at all efficient.  At least it was at the end of the day when it really didn't matter except for when you get home.

Today, I got an answer to the email I sent about the snow bully device.  It sounds like it would be a long shot to be able to use it in the way I envision.  Perhaps I should save my money, huh?  I may ask some more questions, I don't know yet.

Also today:  I asked a young guy about the truth table thing.  He didn't know what one was.  My explanation of it sucked.  I should've drawn a picture.  A picture is worth a thousand words.  He said he knew some other guys at school that he could ask, and I said I would be curious to hear what they said.

You can probably google it.  I did! I did!  ( tweety bird voice )

Here's a video that explains it, but it is screwed up at the end.  It wouldn't have been the way I explained it though, because she is coming from another direction with it.  The way I learned it was from a mathematical point of view.  There were no "if-then-" constructs according to the way I learned it.  There were Boolean Operators.  It's probably not a bad explanation, but the screw up at the end makes it a bit hard to get her point.  I'm not clear after the first time through how this if-then- construct works.  In a programming language, you executed an instruction if the "if" part is true.  Otherwise, you can test another condition called the "else", and if that's true, then execute it.



I told the young fellow that it was a combination of two things taken two at a time.  Which is probably wrong, but hell. It was 40 years ago.  I'm getting it mixed up with probability and statistics.

Basically, you have a condition that is either true or false.  If you have 2 conditions to test against each other, then there are 4 combinations of results depending upon the operator.  An "exclusive or" operator works like this:  If a or b is true, then the result is true.
otherwise, it is false.  That means if both are true, or both are false, the result is false.

It looks like this, where "0" equals false, and "1" equals true.  ( the way a computer represents it )

a         b       result
0         0         0
0         1         1
1         0         1
1         1         0

The significance of the exclusive or operator is that you can do addition with it.  If you add ( in base 2) 0 and 1, you get 1, otherwise you get a zero.  When both are 1, there's a carry, which goes into the bit to the left.


Wishbone dropped in on the conversation, and he was confounded by it all.

Welcome to the wonderful world of computers!  Bwah, hah, hah!

Update:

Since this is a Seinfeld post, or a post about nothing in particular, I add that SpaceX will not attempt the landing of the first stage today.  Since the rocket has already blasted off, this has already not happened.  shucks.

Also, while reading Instapundit, I note that there's a company developing the molten-salt reactor and it is in the USA.  Well, dog my cats, ain't that the dangest thing!  I confused it with the Canadian firm that's doing something quite similar.

Update ( next morning):

SpaceX did a successful soft landing on the ocean itself.  Says it was vertical.  That one got by me.  Oh, well.

Update ( yeah, I know ) :

I should also mention that SpiderFab is making progress---see NBF link above.  A large space sail could be made using a one of these.  With some additional planning, you may even mine an asteroid with one.