Re: [PATCH] pass constants as first argument to st_mult()

Jeff King [off-list ref] writes:

quoted

*1* I have a slight suspicion that this is cultural, i.e. how
arithmetic is taught in grade schools.  When an apple costs 30 yen
and I have 5 of them, I was taught to multiply 30x5 to arrive at
150, not 5x30=150, and I am guessing that is because the former
matches the natural order of these two numbers (cost, quantity) in
the language I was taught.

You might be right. I was trying to figure out what is "natural" for me
in these cases, but after thinking about it for 2 minutes, I'm pretty
sure anything resembling "natural" is lost as I try to out-think myself. :)

Do native English speakers (or more in general Europeans) think of
the apple example more like "5 apples, 30 cents each", and do 5x30?

On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

quoted

*1* I have a slight suspicion that this is cultural, i.e. how
arithmetic is taught in grade schools.  When an apple costs 30 yen
and I have 5 of them, I was taught to multiply 30x5 to arrive at
150, not 5x30=150, and I am guessing that is because the former
matches the natural order of these two numbers (cost, quantity) in
the language I was taught.

You might be right. I was trying to figure out what is "natural" for me
in these cases, but after thinking about it for 2 minutes, I'm pretty
sure anything resembling "natural" is lost as I try to out-think myself. :)

Do native English speakers (or more in general Europeans) think of
the apple example more like "5 apples, 30 cents each", and do 5x30?

I think in my head I rewrite any multiplication like "N of M" as having
"N" as the smaller number. I.e., it is conceptually simpler to me to
count five 30's, then 30 five's (even though I do not implement it in my
head as a sequence of additions, of course; I'd probably do that
particular case as "half of ten 30's").

I have no idea if that's cultural or not, though. I'm pretty sure "half
of ten 30's" was not taught in schools. All I remember of grade school
multiplication is them insisting we write down all of our steps, no
matter how trivial the problem would be to do in our heads. :)

-Peff

On Wed, Aug 03, 2016 at 12:41:30PM -0700, Junio C Hamano wrote:

On Wed, Aug 3, 2016 at 12:13 PM, Jeff King [off-list ref] wrote:

quoted

On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:

I think in my head I rewrite any multiplication like "N of M" as having
"N" as the smaller number. I.e., it is conceptually simpler to me to
count five 30's, then 30 five's (even though I do not implement it in my
head as a sequence of additions, of course; I'd probably do that
particular case as "half of ten 30's").

I have no idea if that's cultural or not, though.

Now, when you say "count five 30's", which one do you have
in mind? 5x30, or 30x5?

If you meant the former, I think that _is_ cultural. I am pretty
sure that I was taught in school(s) to read 5x30 as adding 5
thirty times.

I think I would say "30x5" in that case. But I'm not sure where that
comes from, and I'm not even 100% sure that I would say that (after
thinking about it, it's hard for me to figure out what I would have done
if I _hadn't_ just thought about it).

-Peff

On Wed, Aug 3, 2016 at 12:49 PM, Jeff King [off-list ref] wrote:

On Wed, Aug 03, 2016 at 12:41:30PM -0700, Junio C Hamano wrote:

quoted

On Wed, Aug 3, 2016 at 12:13 PM, Jeff King [off-list ref] wrote:

quoted

On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:

I think in my head I rewrite any multiplication like "N of M" as having
"N" as the smaller number. I.e., it is conceptually simpler to me to
count five 30's, then 30 five's (even though I do not implement it in my
head as a sequence of additions, of course; I'd probably do that
particular case as "half of ten 30's").

I have no idea if that's cultural or not, though.

Well I think there is a difference between how you do the math in your head
and between the textbook question.

In textbook I would expect 5x30, because first we need to talk about the
object before the price of the object makes sense:
"I am interested in 5 apples, and each apple costs 30 yen, so I am paying
150 yen". Only that in Europe you would substitute the 30 by 0.84 Euros
(integer-> number with 2 values after comma, not quite a float).

When doing the math in your head you look for the easy tricks, i.e.
x5  = x10 /2 or such.

I think I'd find calloc intuitive as a typical textbook question, "I
want to have
space for "foos", which each cost 5 memory, go figure out how much I need
and hand it back to me".

On Wed, Aug 3, 2016 at 9:13 PM, Jeff King [off-list ref] wrote:

On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:

quoted

Jeff King [off-list ref] writes:

quoted

quoted

*1* I have a slight suspicion that this is cultural, i.e. how
arithmetic is taught in grade schools.  When an apple costs 30 yen
and I have 5 of them, I was taught to multiply 30x5 to arrive at
150, not 5x30=150, and I am guessing that is because the former
matches the natural order of these two numbers (cost, quantity) in
the language I was taught.

You might be right. I was trying to figure out what is "natural" for me
in these cases, but after thinking about it for 2 minutes, I'm pretty
sure anything resembling "natural" is lost as I try to out-think myself. :)

Do native English speakers (or more in general Europeans) think of
the apple example more like "5 apples, 30 cents each", and do 5x30?

I think in my head I rewrite any multiplication like "N of M" as having
"N" as the smaller number. I.e., it is conceptually simpler to me to
count five 30's, then 30 five's (even though I do not implement it in my
head as a sequence of additions, of course; I'd probably do that
particular case as "half of ten 30's").

I have no idea if that's cultural or not, though. I'm pretty sure "half
of ten 30's" was not taught in schools. All I remember of grade school
multiplication is them insisting we write down all of our steps, no
matter how trivial the problem would be to do in our heads. :)

Yeah, I would be tempted to write all the steps too like this:

"An apple costs 30 yen and I have 5 of them" means:

Cost(1 apple) = 30 cents
Cost(5 apples) = 5 * Cost(1 apple) = 5 * 30 cents = 150 cents

so it would be more "5x30=150" than "30x5" in this case for me.

On Wed, Aug 03, 2016 at 12:59:34PM -0700, Stefan Beller wrote:

I think I'd find calloc intuitive as a typical textbook question, "I
want to have space for "foos", which each cost 5 memory, go figure out
how much I need and hand it back to me".

I think it is more a language question than a math one, though. Is it "5
instances, costing 30 each" or "30-cost instances, 5 times". They are
the same semantically (there is no "30 instances of a 5-cost thing",
which does not map to the problem space), but just with a different
order.

-Peff

On Wed, Aug 3, 2016 at 12:13 PM, Jeff King [off-list ref] wrote:

On Mon, Aug 01, 2016 at 03:31:45PM -0700, Junio C Hamano wrote:

I think in my head I rewrite any multiplication like "N of M" as having
"N" as the smaller number. I.e., it is conceptually simpler to me to
count five 30's, then 30 five's (even though I do not implement it in my
head as a sequence of additions, of course; I'd probably do that
particular case as "half of ten 30's").

I have no idea if that's cultural or not, though.

Now, when you say "count five 30's", which one do you have
in mind? 5x30, or 30x5?

If you meant the former, I think that _is_ cultural. I am pretty
sure that I was taught in school(s) to read 5x30 as adding 5
thirty times.