DaniWeb Forum Index > Software Development > C++

C++ RSS

Anyway can help me to solve this problem???

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Sep 2005

Posts: 14

Reputation: kyakobi84 is an unknown quantity at this point

Solved Threads: 0

kyakobi84

Offline

Newbie Poster

Anyway can help me to solve this problem???

Oct 11th, 2005

What is the code for ( e^x = 1 + x/1! + x^2/2! + x^3/3! + ..... )

anyway can help me, plzzz :cry: :rolleyes:

•

Join Date: Jun 2005

Posts: 2,039

Reputation: Rashakil Fol is just really nice

Solved Threads: 139

Rashakil Fol Rashakil Fol is offline

Offline

Super Senior Demiposter

Re: Anyway can help me to solve this problem???

Oct 11th, 2005

Use a 'for' loop. Show what you think works, and tell us exactly what each line does and why.

In doing this, you'll probably solve your problem, but if that fails, you'll have people here willing to help you.

All my posts may be redistributed under the GNU Free Documentation License.

•

Join Date: Jun 2005

Posts: 4

Reputation: alloy_zeus is an unknown quantity at this point

Solved Threads: 0

alloy_zeus alloy_zeus is offline

Offline

Newbie Poster

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

Are you trying to just get the natural exponential of a number?
There's a function in math library, if I'm not wrong.
Try to see if the math.h of your compiler has a double exp (double) function.

See
http://unixhelp.ed.ac.uk/CGI/man-cgi?exp+3

For microsoft, the function prototype may be different:

http://msdn.microsoft.com/library/de...larray_exp.asp

•

Join Date: Sep 2005

Posts: 14

Reputation: kyakobi84 is an unknown quantity at this point

Solved Threads: 0

kyakobi84

Offline

Newbie Poster

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

thanks for replyiing me,

But i wanna write the code for (e^x = 1 + x/1! + x^2/2! + x^3/3! + ..... ) without using math library.

•

Join Date: Sep 2005

Posts: 14

Reputation: kyakobi84 is an unknown quantity at this point

Solved Threads: 0

kyakobi84

Offline

Newbie Poster

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

Help with Code Tags

(Toggle Plain Text)

#include<iostream.H>

int main()
{

//(e^x = 1 + x/1! + x^2/2! + x^3/3! + .....)

int result = 1;
int x = 2;
int z = 1;
int e = 1;

for (int i = 1 ; i < 4 ; i++)
{

	while ( z != 0)
	{
	result *= z;
	z--;
	}

	//cout << "Result = " << result << endl;
	//cout << "Z = " << z << endl;
	
	e = e + x^i/result;

	z++;
}

cout << "The Sum = " << e << endl;

return 0;
}

<< moderator edit: added code tags: [code][/code] >>

The Bold font is the factorial part & its not working well, i need to fix tht, plz help (i dont wanna use any function)[I][U]

•

Join Date: Aug 2005

Posts: 80

Reputation: Daishi is an unknown quantity at this point

Solved Threads: 2

Daishi

Offline

Junior Poster in Training

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

I think you know how to take a factorial of a number, but your variable usage is not good.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
while ( z != 0)
{
result *= z;
z--;
}
while ( z != 0)
{
result *= z;
z--;
}

Now, honestly, that works if you first set z to the value of whatever you want to take the factorial of, and set result to one. You're setting z equal to one before the for loop, and then incrementing it at the end of each loop, but you decrement it to zero before that, so your while loop is *entirely pointless*.

Just multiply result by i, you don't need a while/for loop or whatever.

-Fredric

•

Join Date: Sep 2005

Posts: 14

Reputation: kyakobi84 is an unknown quantity at this point

Solved Threads: 0

kyakobi84

Offline

Newbie Poster

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include<iostream.H>
 
int main()
{
 
//(e^x = 1 + x/1! + x^2/2! + x^3/3! + .....)
 
int result = 1;
int x = 2;
int e = 1;
 
for (int i = 1 ; i < 4 ; i++)
{
 
	result *= i;
 
	//cout << "Result = " << result << endl;
 
	e = e + x^i/result;
 
}
 
cout << "The Sum = " << e << endl;
 
return 0;
}
#include<iostream.H>

int main()
{

//(e^x = 1 + x/1! + x^2/2! + x^3/3! + .....)

int result = 1;
int x = 2;
int e = 1;

for (int i = 1 ; i < 4 ; i++)
{

	result *= i;
	
	//cout << "Result = " << result << endl;
	
	e = e + x^i/result;

}

cout << "The Sum = " << e << endl;

return 0;
}

<< moderator edit: added [code][/code] tags >>

You mean like this???

•

Join Date: Aug 2005

Posts: 80

Reputation: Daishi is an unknown quantity at this point

Solved Threads: 2

Daishi

Offline

Junior Poster in Training

Re: Anyway can help me to solve this problem???

Oct 14th, 2005

I didn't see it the first time, but the ^ doesn't do what you think it does in C++, if you want to take m to the n power then you use the pow function like so...

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <math.h>
 
...
 
double m=2.0, n=3.0, result;
result = pow(m, n);
#include <math.h>

...

double m=2.0, n=3.0, result;
result = pow(m, n);

That would return 2 to the 3rd, or 8. Hope that helps a bit.

-Fredric

•

Join Date: Jun 2005

Posts: 4

Reputation: alloy_zeus is an unknown quantity at this point

Solved Threads: 0

alloy_zeus alloy_zeus is offline

Offline

Newbie Poster

Re: Anyway can help me to solve this problem???

Oct 18th, 2005

Hi, I have some issues with your variable names. result is actually not the result, and e is actually the natural log constant in your comments. Made some changes to the var and trying to do away with the pow fn.
Not sure if you want to restrict your input to just integral values, but output will most definitely be double?

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
int main()
{
 
  //(e^x = 1 + x/1! + x^2/2! + x^3/3! + .....)
 
  double x = 2.0; // input value
 
  int factorial = 1;
  double pow_x = 1.0;
  double result = 1.0;
 
  cout << "e^" << x << " = 1";
 
  for (int i = 1 ; i < 4 ; i++)
  {
 
	factorial *= i;
	pow_x *= x;
 
	cout << " + " << pow_x << "/" << factorial;
 
	result = result + pow_x/factorial;
 
  }
 
  cout << endl << "= " << result << endl;
 
  return 0;
}
int main()
{

  //(e^x = 1 + x/1! + x^2/2! + x^3/3! + .....)

  double x = 2.0; // input value

  int factorial = 1;
  double pow_x = 1.0;
  double result = 1.0;

  cout << "e^" << x << " = 1";

  for (int i = 1 ; i < 4 ; i++)
  {

	factorial *= i;
	pow_x *= x;
	
	cout << " + " << pow_x << "/" << factorial;
	
	result = result + pow_x/factorial;

  }

  cout << endl << "= " << result << endl;

  return 0;
}