Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

recursive problem

Posted on 2008-10-05
11
Medium Priority
?
307 Views
Last Modified: 2012-05-05
I have a recursive program that is suppose to return the square root of a number recursivley, the program will run, but it returns 1. please help
#include <stdio.h>
 
 
 
double square_root(double low, double high);
 
int main(void)
{
    float number;
    double root;
    
    printf("Enter a number to compute the square root of.\n");
    scanf("%f", &number);
    
    root = square_root(1, number);
    
    printf("The square root of %.3f is about %.3lf\n", number, root);
    
    system("PAUSE");
    return 0;
}
 
	double square_root(double low, double high)
{
    float mid;
    
    mid = (high + low) / 2;
 
    //Base Case
    if((mid*mid) == high)
        return mid;
 
     //Stops when the high and low numbers are within 0.001 of one another.   
    if((high - low) < 0.001)
        return mid;
    
    if((mid*mid) > high)
        return square_root(low, mid);
        
    return square_root(mid, high);
}

Open in new window

0
Comment
Question by:mikeregas
  • 4
  • 3
  • 2
  • +1
11 Comments
 
LVL 85

Expert Comment

by:ozo
ID: 22646982
Are you sure you have the correct recursion?
The method you use looks like it would work better passing 3 numbers.
or else changing
0
 

Author Comment

by:mikeregas
ID: 22647108
I need to take a number say 19.7 and then it is suppose to return 4.438 is the example that I was given. I know that I am suppose to take two number the low which would be 0 and the high and which would be 19.7 and recursively bring it down to an approximate square root. So there would be a third number in the equation the  mid.
0
 
LVL 45

Expert Comment

by:sunnycoder
ID: 22647118
>square_root(1, number);
second arg is the number whose sq root you want.

Your recursive calls are
>return square_root(low, mid);<<<------ you are calculating sq root of mid!!
>return square_root(mid, high);

0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 1

Expert Comment

by:lakshmikarle
ID: 22647340
Hello mikergas,

You are using "Babylonian method" to calculate square root. You are not using it in right way.
For proer desciption of babylonian method can be found in link
http://personal.bgsu.edu/~carother/babylon/Examples.html

I am attaching modified and working version of your code..
<code edited out>
sunnycoder
ZAPE

Open in new window

0
 
LVL 1

Expert Comment

by:lakshmikarle
ID: 22648784
sunnycoder,
I will take care in future
0
 

Author Comment

by:mikeregas
ID: 22650155
I am confused on what is right in my code and what is wrong? can you please give me some direction to go in. my code is return a 1 for any number that I input and I know that is worng.
0
 
LVL 45

Expert Comment

by:sunnycoder
ID: 22650289
http:#22647118 lists your problem
http:#22646982 hints at a solution
0
 
LVL 1

Expert Comment

by:lakshmikarle
ID: 22650877
According to algorithm
x(n+1) = 1/2( x(n) + a / x(n) )

where a is the number for which square root should be calculated.
Change calculation of 'mid' to above formula.

Also, since you are always calling function recursively with low as 1, your answer is always converging to 1.

0
 

Author Comment

by:mikeregas
ID: 22651030
x(n+1) = 1/2( x(n) + a / x(n) ) let me make sure that I understand this. if a is the number that I am trying to get the root of then x is a function of what? I am truely lost with recursion
0
 
LVL 1

Accepted Solution

by:
lakshmikarle earned 1500 total points
ID: 22651108
n can take values like 0,1,2,3
Assume x(0) = 1.
Go thru the link I have posted
0

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Windows programmers of the C/C++ variety, how many of you realise that since Window 9x Microsoft has been lying to you about what constitutes Unicode (http://en.wikipedia.org/wiki/Unicode)? They will have you believe that Unicode requires you to use…
The goal of this video is to provide viewers with basic examples to understand recursion in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use switch statements in the C programming language.

916 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question