math question in C++

[phantomAI]

How do I do pi and square a number in C++?

[Tesseract]

Not sure about pi, but for squaring a number put "^ 2" after it w/o quotes.

[Joseph Zollo]

PI is 22/7, if you're taking AP Computer Science you should get into the habit of declaring it as a constant.

<pre>const double PI=22/7;</pre>

To square a number, just multiply it by itself. Let's say x=5

<pre>x*x (returns 25)</pre>

if you want to get a square root, you need to #include and use the sqrt(); function.

<pre>sqrt(25); //returns 5</pre>

Hope that helps!

[Tesseract]

Problem with saying that is is 22/7 is that it's not exactly pi, but I imagine it is close enough. :p

[Evolution]

  Quote

Originally posted by JZolloXP

PI is 22/7, if you're taking AP Computer Science you should get into the habit of declaring it as a constant.

<pre>const int PI=22/7;</pre>

To square a number, just multiply it by itself. Let's say x=5

<pre>x*x (returns 25)</pre>

if you want to get a square root, you need to #include and use the sqrt(); function.

<pre>sqrt(25); //returns 5</pre>

Hope that helps!

22/7 is not pi, it may have the first 3 digits correct, but the rest are all wrong. Thought 22/7 is regarded as computer programmers, and I am astounded on why they chose such an inaccurate ratio, as in computer science even having a few digits off could freeze up everything.(ie recursive loops).

At least 52163/16604 is accurate to 7 digits :) But to truely find pi, you must create a program for it :)(hint: the program will be a recursive program)

[Joseph Zollo]

  Quote

Not sure about pi, but for squaring a number put "^ 2" after it w/o quotes.

I just tried doing that (i didn't know ^ was an exponet operator) and it wouln't work...here's my code

<pre>

#include <iostream.h>

#include <math.h>



void main()

{

	cout << (4^2) << endl;

}

</pre>

It returns 6 for some odd reason :paranoid:

[Tesseract]

  Quote

Originally posted by JZolloXP

I just tried doing that (i didn't know ^ was an exponet operator) and it wouln't work...here's my code

<pre>

#include <iostream.h>

#include <math.h>



void main()

{

	cout << (4^2) << endl;

}

</pre>

It returns 6 for some odd reason :paranoid:

Odd indeed......should be exponent but it performs the operation as if 4 and 2 were being added. :ponder:

[Evolution]

  Quote

Originally posted by JZolloXP

I just tried doing that (i didn't know ^ was an exponet operator) and it wouln't work...here's my code

<pre>

#include <iostream.h>

#include <math.h>



void main()

{

	cout << (4^2) << endl;

}

</pre>

It returns 6 for some odd reason :paranoid:

wooohooo my c interpreter is way different from yours :) I have no idea what cout and :p)

[Evolution]

hehehe I just found a pi program off the internet :p Now this is great ;)

http://remus.rutgers.edu/~rhoads/Obfuscated_C/pi.c

hahaha, well at least I'll give him creativity marks :)

[DeathLace]

the program can just be this for squaring pie:

#include

#include

void main()

{

const double pi = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808;

cout << pi^2 << endl;

}

[Joseph Zollo]

  Quote

Originally posted by DeathLace

the program can just be this for squaring pie:

#include

#include

void main()

{

const double pi = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808;

cout << pi^2 << endl;

}

Maybe it's just me but the ^ operator isn't working at all, when I compile the above program it gives me this error

error C2297: '<<' : illegal, right operand has type 'class ostream &(__cdecl *)(class ostream &)'

When I take out the ^, everything works fine. I'm using Visual C++ 6 in case you're wondering...

[Evolution]

  Quote

Originally posted by DeathLace

the program can just be this for squaring pie:

#include

#include

void main()

{

const double pi = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808;

cout << pi^2 << endl;

}

ooooh, now you're really calculating pi....hmmmm somehow I consider that cheating :p Oh well :)

[phantomAI]

thanks for the replies :D , couldn't believe that I wasn't thinking about multiplying the variable to itself for square. Yeah, pi is a hassle.

[DrunkenMaster]

Seems to me if you do this:

const double pi =

3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808;

you're going to run into a lot of floating point inaccuracies. How many digits do you really need to be accurate to? If you use say 8-10 digits of precision it should probably be enough.

[xWeston]

  Quote

Originally posted by Tesseract

Not sure about pi, but for squaring a number put "^ 2" after it w/o quotes.

Where did you learn how to program? The ^ operator is reserved for XOR

the easiest way to raise something to a power is to use the pow() function

pow(4,2); is the same as 4^2 on a calculator

i think you need to include math.h

[xWeston]

  Quote

Originally posted by Evolution

hehehe I just found a pi program off the internet :p Now this is great ;)

http://remus.rutgers.edu/~rhoads/Obfuscated_C/pi.c

hahaha, well at least I'll give him creativity marks :)

That is mild compared to a lot of the programs in the obfuscated C contest

[Kenno]

  Quote

Originally posted by xWeston

Where did you learn how to program? The ^ operator is reserved for XOR

the easiest way to raise something to a power is to use the pow() function

pow(4,2); is the same as 4^2 on a calculator

i think you need to include math.h

I agree, you can't use 4^2 to represent 4 square.

[RFrost]

I've never seen ^ used for squaring numbers except on graphing calculators. I've always just used pow(#,#); whenever I needed a power done. And I'm not sure, but with Visual Studio 6 I think there's a .h file that MS included with the package that has pi calculated out to the right number of digits for accurate floats.

[kellyt]

1. Very fewcomputers use more 16 digits to represent a double. You don't need to put 60 digits in your const definition.
   
2. An easy way to calculate pi would be to use the atan function. Remember your H.S. geometry? tan( pi ) == 1/4. This function is easier than memorizing 16 (or 60!) digits of pi. Plus, it also provides you with the most accurate representation of pi for the machine you are working on.
   

<pre>

#include <iostream>

#include <cmath>



using namespace std;



int main()

{

   const double pi = 4.0 * atan( 1.0 );

   cout << "Pi = " << pi << endl;

   return 0;

}

</pre>

This code will work for compilers that conform to the C++ standard. I used g++ 3.2 to test this piece of code.

-kt

  Quote

Originally posted by DeathLace

the program can just be this for squaring pie:

#include

#include

void main()

{

const double pi = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808;

cout << pi^2 << endl;

}

[AMDTBurnt]

god n00bs, you don't use ^ for powers, you use that in the BASIC programs in your calculators retards. Use the pow() function or multiply it by itself.