use sharps approximation formula to calculate PI

[james121285]

This is my first ever program. I have struggled big time and its token so long my university lab is closed, can someone please check this over and maybe even correct some parts. I would be so happy if someone could. Thanks

The assignment is to use sharps approximation formula to calculate PI, which is a continous formula until n = k. The second part is to use M_PI and take away the approxiamtion formula, and print both.

#include <stdio.h>
#include <math.h>

int main (void)
{
   float part1, part2, part3, numerator, n;
   int k;

   printf ("Please input number of iterations");
   scanf("%d",&n);

   for (k = 0; k <= n; k++);
   {
      if (k%)
         numerator = -1.0;
      else numerator =1.0;

      part1 += numerator / (3pow k)* ((2* k) +1);

      part2 = 3.464101615 * part1

      part3 = M_PI - part2

      printf ("%f, %f", part2, part3);

   }
}

[willakawill]

Here are the errors in your code after I have repaired some typos:

int main (void)

{
	float part1, part2, part3, numerator, n;
	int k;

	printf ("Please input number of iterations");
	scanf("%d",&n);

	for (k = 0; k <= n; k++);
	{
		if (k%)
			numerator = -1.0;
		else numerator =1.0;

		part1 += numerator / (3pow k)* ((2* k) +1);

		part2 = 3.464101615 * part1;

		part3 = M_PI - part2;

		printf ("%f, %f", part2, part3);

	}
	return 0;
}

Testall.cpp(19) : error C2059: syntax error : ')'
Testall.cpp(21) : error C2181: illegal else without matching if
Testall.cpp(23) : error C2059: syntax error : 'bad suffix on number'
Testall.cpp(23) : error C2146: syntax error : missing ')' before identifier 'pow'
Testall.cpp(23) : error C2059: syntax error : ')'
Testall.cpp(27) : error C2065: 'M_PI' : undeclared identifier

[james121285]

Could someone help me by fixing these fault codes or even tell me what they mean and how to fix them. I am a real novice at this. Thank you.

[willakawill]

Could someone help me by fixing these fault codes or even tell me what they mean and how to fix them. I am a real novice at this. Thank you.

So where did you get the code that you posted?

[horace1]

Could someone help me by fixing these fault codes or even tell me what they mean and how to fix them. I am a real novice at this. Thank you.

you are getting close - i have fixed a couple more errors and it now compiles, see if it works!

#include <stdio.h>
#include <math.h>

int main (void)

{
	float part1, part2, part3, pow3=1, numerator, n;
	int k;

	printf ("Please input number of iterations");
	scanf("%d",&n);

	for (k = 1; k <= n; k++);
	{
		if (k%2)                  // ** added 2
			numerator = -1.0;      // ** odd
		else numerator =1.0;       // ** even
                pow3=  pow3*3;            // ** added
		part1 += numerator / (pow3)* ((2* k) +1);
  }
		part2 = 3.464101615 * part1;

		part3 = M_PI - part2;

		printf ("%f, %f", part2, part3);

	// remove }
	return 0;
}

[james121285]

Well the program I tried to write came from various sources. The notes I have are very basic and I found a couple of examples on the net. They were not the examples I was looking for, but I thought I could modify them and hope they would work. I know its not the best idea, and I am planning on buying a couple of books on Monday to help me, but until then, am realy stuck.

[horace1]

Well the program I tried to write came from various sources. The notes I have are very basic and I found a couple of examples on the net. They were not the examples I was looking for, but I thought I could modify them and hope they would work. I know its not the best idea, and I am planning on buying a couple of books on Monday to help me, but until then, am realy stuck.

you can check your results by looking at section 2.2.1 of

http://numbers.computation.free.fr/Constants/Pi/piclassic.html

where it gives PI with 1, 2, 5 and 10 iterations

[james121285]

Thanks for your help, you have made my day. One more question, can you recommend any good C++ program books. I would love to learn more about this.
Thanks again.

[horace1]

Thanks for your help, you have made my day. One more question, can you recommend any good C++ program books. I would love to learn more about this.
Thanks again.

there are still some semantic errors in the last code I posted, e.g. look at the scanf() and remove the ; on the end of the for()

have a look at this tutorial

http://www.cplusplus.com/doc/tutorial/

[james121285]

I am having a slight problem with the ouput results. I have traced it back to the pow3, this section has to be 3 to the power of k, which will increase on every interaction, until it matches the number of interations the user has put in. How would I be able to do this.

[horace1]

I am having a slight problem with the ouput results. I have traced it back to the pow3, this section has to be 3 to the power of k, which will increase on every interaction, until it matches the number of interations the user has put in. How would I be able to do this.

fixed a couple of more errors (indicated by comments), try it now

#include <stdio.h>
#include <math.h>

int main (void)

{
	double part1=1, part2, part3, pow3=1, numerator;
	int k, n;   // ** changed n to an int to suit the scanf() and for()

	printf ("Please input number of iterations");
	scanf("%d",&n);

	for (k = 1; k < n; k++)//; removed ;
	{
		if (k%2)                  // ** added 2
			numerator = -1.0;      // ** odd
		else numerator =1.0;       // ** even
        pow3=  pow3*3;            // ** added
		part1 += numerator / (pow3* ((2* k) +1));
 		printf ("%f, %d\n", pow3, ((2*k)+1));
      }
		part2 = 3.464101615 * part1;

		part3 = M_PI - part2;

		printf ("%f, %f", part2, part3);
getchar();getchar();
	// remove }
	return 0;
}

[james121285]

I have just tried it. It works perfectly, thanks. Your a star horace1.

Thanks again.

James

[ashith]

Nice program