while loop perfect square

[Raymond]

I'm trying to write a while loop to count the number of perfect squares between 1 and N. Let's set the number of perfect squares as the variable y.

x=1;
y=0;
while x:N
if mod(sqrt(x), 1)==0;
y=y+1
end
x=x+1
end

This is roughly what I'm trying to do. Can you guys show me my errors and how to fix them? Thanks as always.

[Raymond]

[ImageAnalyst]

Your while statement was wrong. You wanted x<N, not x:N (which is a
long vector). Try this:

N = 70;
x = 1;
while x <= N
if rem(sqrt(x), 1) <= eps
fprintf('%d is a perfect square.\n', x);
else
fprintf('%d is NOT a perfect square.\n', x);
end
x=x+1;
end

[Raymond]

nevermind figured it out

[Raymond]

nevermind figured it out. double post was a mistake. computer lagging. no intent

[Royi Avital]

"Raymond " <atlantasw...@yahoo.com> wrote in message <i808iu$723$1...@fred.mathworks.com>...

I would go:

x = 1;
y = 0;

while x <= N
if rem(sqrt(x), 1) <= eps

y = y + 1;
x = x + sqrt(x);
end
x = x + 1;
end

Since if x is a perfect square no other "Perfect Square" would be in sqrt(x) range.

[ImageAnalyst]

Yeah, nice trick to speed it up. But since no floating point number
would be a perfect square of an integer, wouldn't you do

x = x + ceil(sqrt(x));

For even more speedup, we could do
x=(sqrt(x)+1)^2 - 1 % ;-)

and I still don't know why that "y" is in there.

[Royi Avital]

ImageAnalyst <imagea...@mailinator.com> wrote in message <4d675c46-e9fd-491b...@i5g2000yqe.googlegroups.com>...

Yea, You got where I got my Speed Up idea from :-).

It is recommended to use you corrections.

[Matt Fig]

This might be faster, yet still a WHILE loop.

count = 1;
while count<= sqrt(N)-1
count = count + 1;
end

[Steven_Lord]

"Matt Fig" <spam...@yahoo.com> wrote in message
news:i80pq8$g8q$1...@fred.mathworks.com...

If you were looking to do this without SQRT, you could use the second
equation given on this page:

http://en.wikipedia.org/wiki/Square_number

function numSquares = countsquares(N)
numSquares = 0;
currentSquare = 1;
increment = 3;
while currentSquare <= N
numSquares = numSquares + 1;
currentSquare = currentSquare + increment;
increment = increment + 2;
end

This handles negative and noninteger values for N; add error checking for
complex, nonfinite, or nonscalar N to taste.

--
Steve Lord
sl...@mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
To contact Technical Support use the Contact Us link on
http://www.mathworks.com

[Matt J]

"Raymond " <atlantasw...@yahoo.com> wrote in message <i808iu$723$1...@fred.mathworks.com>...

> I'm trying to write a while loop to count the number of perfect squares between 1 and N.

====

Why? Isn't the answer always floor(sqrt(N))

[raman]

write a c program to display perfect square &cube?

[ImageAnalyst]

On Nov 20, 6:11 am, raman <u...@compgroups.net/> wrote:
> write a c program to display perfect square &cube?

-------------------------------------------------------------------------------------
You write a sentence in the imperative mood (http://en.wikipedia.org/
wiki/Grammatical_mood) yet you add a question mark indicating it's in
the interrogative mood. I have no idea if you're demanding that we
perform some task for you, or if you're asking us a question.

[Steven_Lord]

"ImageAnalyst" <imagea...@mailinator.com> wrote in message

news:3e598046-0b28-431d...@p1g2000yqm.googlegroups.com...

In either case, since the message refers to C but not MATLAB, the message
should probably have been posted on a different newsgroup like comp.lang.c
(or should not have been posted at all.)

--
Steve Lord
sl...@mathworks.com