I need a simple and working algorithm for finding out the squareroot of a number (preferably a 4 digit number)

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Hello everyone,
i need a simple algorithm for finding out square root a 4 digit number...
I know how to find out it on PAPER but designing algorithm is not being successful...plz help me out..

Posted 27-Jul-13 19:08pm

Dinesh92

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Sergey Alexandrovich Kryukov 28-Jul-13 1:55am

Homework?
—SA

bbirajdar 28-Jul-13 5:13am

My suggestion to all the people who post code to homework type questions-

Its the codeproject's unwrittem policy not to spoon feed or provide code to homework type of questions. In those cases proper guidance or references are expected on the basis of which the person who posts the question can move ahead a step, study and implement it on his own. The motive behind this is to help him learning and not just make him copy paste the code and execute it without understanding.

I always remember the chinese proverb whenever I see these types of questions -"Give a man a fish and he will eat for a day. Teach him how to fish and he will eat for a lifetime.”

No offence against anybody. But I have always seen the most senior members on CP never post code to homework type of questions and I try to follow them. So I never vote these solutions even if they are correct (my own policy).

Sergey Alexandrovich Kryukov 28-Jul-13 12:04pm

If you posted it as an answer, I believe it would be the best answer so far.
—SA

H.Brydon 28-Jul-13 22:48pm

I believe it is "Give a man a fish and he will eat for a day. Teach him how to fish and he will eat for a lifetime. Show him how to use Google and he will never bother you again.”

Sergey Alexandrovich Kryukov 3-Jun-15 21:15pm

Those words about feeding a fish are golden.
And by the way, I hope you will like my own saying as well:
Feeding Apple or Why Don't We Answer Some Questions.
—SA

H.Brydon 3-Jun-15 22:42pm

I like your "golden apple" angle as well. :-)

Sergey Alexandrovich Kryukov 3-Jun-15 22:52pm

Great.
Sorry, I think I failed to invite you to read my 1st of April article of 2015. I remembered that I'm missing someone, and I certainly wanted to invite your, but I forgot who else I was missing at that time. :-(.

Here: Some Programming Approaches to "Neuro-Linguistic Programming".
And this is the previous one, just in case: Power Over IP: Testing of the First Experimental Facility.

I think we really need this 1st of April tradition, if even IETF is keeping it; and we are missing it. Many told me they enjoy my little jokes and the hoax, hope you will like it, too. Sorry I was so late.

—SA

Stefan_Lang 30-Jul-13 5:10am

You haven't responded to any of the solutions or comments. After looking at Solution 1, I wonder if your request was limited to calculations with integers? That would be an important factor to know, as the nature of the problem changes considerably: restricted to integers this is a number theory problem; with floating point values it is a numerical problem.

3 solutions

Solution 4

I know there is a method for calculating the square root manually, but that one ins not particularly useful for calculating it on a computer. Computers can multiply and divide numbers with many digits and the execution time is nearly the same, no matter the factor are a single digit or contain many decimal places.

One of the easiest square root algorithms for a computer is the so-called Babylonian method (in fact an application of the Newton algorithm for solving an equation):

C++

x = 0.5 * (x + s/x);

s being the number that you want to take the square root of. See http://en.wikipedia.org/wiki/Square_root_algorithm[^].

For the starting value you might choose x=s/4. Four iterations of the above formula should give you a precision of about 6 significant digits.

Posted 27-Jul-13 23:02pm

nv3

Updated 28-Jul-13 20:14pm

v2

Comments

Joezer BH 28-Jul-13 5:09am

5ed!

this method is being taught in Universities as an example of simplicity in algorithms which could otherwise have been complicated, while this is not an exact answer, you would easily produce a "close to" answer with the appropriate precision, if you take 20 iterations for instance that would probably suit even NASA calculations

nv3 28-Jul-13 5:56am

Thank you.

Solution 2

Do something like this:

C#

double square_root(double low, double high)
{
    double mid, result = 0.0;

    mid = (high + low) / 2;

    //Base Case
    if((mid*mid) == high) {
        result = mid;
    } else if((high - low) < 0.001) {
        //Stops when the high and low numbers are within 0.001 of one another.
        result = mid;
    } else if((mid*mid) > high) {
        result = square_root(low, mid);
    } else {
        result = square_root(mid, high);
    }
    return result;
}

Or,
See..
http://edisontus.blogspot.com/2013/04/square-root-algorithm-for-c.html[^]

Posted 27-Jul-13 19:51pm

ridoy

Comments

Stefan_Lang 29-Jul-13 10:39am

So, ... what is the square root of 0.25 again?

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Sergey Alexandrovich Kryukov · Accepted Answer · 2013-07-27T19:54:00

Solution 3

Such algorithm is already implemented in the CPUs. That said, it looks like your problem is not a real problem, but the one posed for educational purpose. It means that, most likely, this is some kind of home assignment, and this one is a pretty interesting one.

Will it help you if someone does your home assignment for you? I don't think so. Not only you need yet another credit, but you really need education. By not doing your assignment by yourself, you are loosing yest another chance to get some more knowledge and experience. And loosing this chance is not good for your. So, use your chances which your school gives you.

—SA

Posted 27-Jul-13 19:54pm

Sergey Alexandrovich Kryukov

Comments

nv3 28-Jul-13 4:45am

Not all CPUs have a build-in instruction for square-rooting. So I would not be all that harsh with the guy. I just wonder, why he hasn't taken a look into Wikipedia.

Sergey Alexandrovich Kryukov 28-Jul-13 12:25pm

Thank you for your note. Yes, it shows that my speculations were not quite accurate, but I don't think the fix of them could shake my logic. Well, most systems where such calculations are needed, standard libraries, etc.

Maybe you are right about some harshness, you never know exactly how to deal with people in some situations, but I personally think it's just right. Note that I never characterize the person in any negative way. I would not have any right to say something like that: he just asked a question, it should not be discouraged. I'm only giving OP the advice, what to do with this situation.

—SA

nv3 28-Jul-13 13:27pm

No problem, Sergey. You are in general a very good tutor.

Sergey Alexandrovich Kryukov 28-Jul-13 14:36pm

Agree, no problems. Thank you for your nice words...
—SA

bbirajdar 28-Jul-13 5:03am

+5 for the guidance...

Sergey Alexandrovich Kryukov 28-Jul-13 12:21pm

Thank you very much.
—SA