Re: LF: PRIME NUMBERS!
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Re: LF: PRIME NUMBERS!
On Thu, 12 Dec 1996, Kevin T. Huber wrote:
>
> Of course if you did a simple test for division by 2 and incremented c by 2
> you would double the performance. You also recalculate the square root of
> x every iteration when you could have assigned it to a variable. Also it
actually, you're wrong. the first test checks for 2 as a factor, so it
DOES test for division by two. if you incremented c by 2 after the first
test, that might help, yes. if you'd paid a little more attention, you'd
notice that x changes its value, so using a precalculated variable
wouldn't work.
> appears from inspection that the routine won't work for repeated factors
> (i.e. 8=2*2*2) since you don't reinitialize c. In other words, this
wrong again. it loops for the same value of c, so it would list, 2, find
2 again, find 2 again, and then stop.
> routine is worthless.
sorry, you lose. pay a little bit better attention to what you're talking
about next time you critique someone's code. I don't enjoy material I
present being called worthless by someone that can't interpret code
correctly.
> > TI-82 programming:
> >
> > Input x
> > 2->c
c starts as two, so the first check is a divide by two
> > Lbl 1
> > If c> sqrt(x) //sqrt(n) -- take the square root
> > Goto 2
> > If fpart (x/c)=3D0 then x/c -> x // fpart means the part after the decimal
x changes its value in the previous line.
> > Disp c // display the value of c
> > goto 1
c is still its current value when the program loops to check for that
number again.
> > end // ends if-then statement
> > c+1 -> c
> > goto 1 //if if statement was false, increment c and goto 1
> > lbl 2
> > if x>1 disp x
> >
> > :end program
again, check the code you're reading more carefully before you start
criticizing.
Jonathan Dickmann
email:jdickman@rhf.bradley.edu
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