On Wednesday, 31 July 2013 at 22:58:56 UTC, Walter Bright wrote:
On 7/31/2013 2:40 PM, Bill Baxter wrote:
Are you serious that you can't fathom how it could be
confusing to someone than
talking about differences in run times?
And no, I'm not talking about confusing to someone who lives in
an undiscovered stone age tribe in the Amazon. I'm talking
about computer programmers.
If you say something is faster than something else you want
the two numbers to
be something you can relate to. Like MPH. Everyone has a
clear concept of what
MPH is. We use it every day. So to say 25 MPH is 25% faster
than 20 MPH is
perfectly clear. But nobody talks about program execution
speed in terms of
programs per second.
Yes, they do, and certainly in "lines per second". Google it
and see for yourself. And as you well understand, from using
the same program to compile, the number of lines cancels out
when comparing speeds.
There is nothing mysterious or confusing about this. Seriously.
So I think it's pretty clear why that would be harder for
people to grok than changes in car speeds or run times.
To be blunt, Baloney!
Can we please stop this dumb argument?
I think the source of the confusion is that programmers only use
execution times to measure execution speed and will often say
that they sped up a program by 50% when they halved the execution
time, implying that the "speed" went up by 50%. Well, as Walter
points out, a real speed, ie output/sec, would go up 100% in that
scenario, so the programmers' language is technically incorrect.
This breaks many programmers' intuitions, hence all the
complaining in this thread.
However, this whole debate is a bikeshed topic, as nobody really
cares if the gain was 43% or 75%, ie nobody is using that
precision for any purpose anyway. Walter is technically correct,
that's all that matters.
On Wednesday, 31 July 2013 at 23:26:32 UTC, Walter Bright wrote:
No real electrical engineer would ever use that card, as you
connote with your quotes. If they don't have Ohm's law and the
resulting algebra drilled into their head, they better find
another job. I suspect that chart is for amateurs from other
backgrounds who happen to be doing some electrical work.
On 7/31/2013 3:58 PM, John Colvin wrote:
It's a quite impressively unbalanced education that provides
memory allocation strategies, hashing and the performance
pitfalls of integer
division, but not something as basic as a speed.
Have you ever seen those cards that some "electrical engineers"
carry around, with the following equations on them:
V = I * R
R = V / I
I = V / R
I found it:
Unbelievable. The author of it writes:
"I'm going to explain to you how to use this cheat sheet in
case you've never seen this before."
Makes you want to cry.