Make a program to calculate pi to the n'th decimal. Input the variable at runtime. Program In the language of you choice. (and none of the print"3.1415" crap.)
series n = s / (2 * n + 1)
where s | even n = 1
| odd n = -1
pi-aproximations = map series [0.0..]
accurate nth (a,b) = abs (a - b) < 10 ^^ (-1 * nth)
pi nth = head (filter (accurate nth) (zip pi-aproximations (tail pi-aproximations)))
lol noone is smart enough to do it. good challenge
Name:
Anonymous2007-09-14 1:37 ID:Ieoi1S0b
(defun pi () (/ 22 7))
Nice challenge, lol.
Name:
Anonymous2007-09-14 2:17 ID:L/6D3QNO
#include <stdlib.h>
#include <stdio.h>
void ComputePi(int numdigits, char* pi)
{
int alength = 10 * numdigits / 3;
int* a = (int*) malloc(alength * sizeof(int));
int piLength = 0;
int nines = 0;
int predigit = 0;
int i, j;
for(i = 0; i < alength; ++i)
a[i] = 2;
for (j = 0; j < numdigits; ++j)
{
int q = 0;
int p = 2 * alength - 1;
for (i = alength; --i >= 0; )
{
int x = 10*a[i] + q*(i+1);
a[i] = x % p;
q = x / p;
p -= 2;
}
>>14
I remember an episode of "Jim'll Fix It" in the late 80s where a nerdy young girl wrote in asking him if he could fix it for her to calculate the value of Pi. So they brought her in the studio and had her calcuate 22/7 to about 50 decimal places. I lol'd.
You need to end your input with an EOF (usually ^D or ^Z, depends on your implementation and OS). Also, if your implementation is slow it can take a while.
>>39
your code in that link does not work
Error: value at [4] smaller than 0
I'm using my own implementation, i typed 3^D and i got 85714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714285714
etc etc, is that supposed to be the output of `3'?
Please mention if the memory can be looped (eg < is the last cell) and what value the cell has if EOF is read
My implementation allows < (or > in the end) and EOF = 0
Name:
Anonymous2007-09-14 10:48 ID:WWWs1FtP
It works on that link (Firefox and IE tested), put a number (and nothing else) in the input field. I don't exactly put error handling in brainfuck.
That implementation is very strict and if it works there, it should work everywhere. No moving to before memory cell 0, no overflowing or underflowing. EOF = 0. Moving past 30000 is allowed to be Turing complete, but this program doesn't go there by far.
Only issue with my code is that the highest number you can input is 254 before the counter overflows. I guess it gets weird input on your implementation.
And yes, it's supposed to output 3.142857 repeating. That's 22 / 7, it's pretty hard to really calculate pi in brainfuck.
>>41 It works on that link (Firefox and IE tested), put a number (and nothing else) in the input field.
Ah, now it works
Very nice work.
Name:
Anonymous2007-09-14 13:09 ID:p0bpMm5E
It's really too bad that in the real world, you never have to do stuff like calculate Pi or factorials, because that's pretty much the only thing useless toy languages really shine at.
>>27 >>44
This ``challenge'' is officially crap. Methods of pi digit extraction are no secret, and most are trivial to implement. This tests your ability to use Google and nothing else.
>>50
It would also be any one of these
1
10
100
10000
1000000000000000000000
Name:
Anonymous2007-09-14 22:13 ID:MPVsRCXO
<?php
get_pi();
?>
winrar
Name:
Anonymous2007-09-14 22:14 ID:pmk4hbO8
Protip: Use Manchin's formula:
pi = 4*(4*arctan(1/5) - arctan(1/239))
If you want it more precise:
pi = 4*(183*atan(1/239)+32*atan(1/1023)-68*atan(1/5382)+12*atan(1/113021)-100*atan(1/6826318)-12*atan(1/33366019650)+12*atan(1/43599522992503626068))
Use modulus division to get the digit you want. Trivial.
But, let's get serious... pi to 30 digits is enough to compute the visible universe with almost no error. For most cases, you don't need lots of digits. It's a parlor trick.
Next?
Name:
Anonymous2007-09-14 22:16 ID:pmk4hbO8
>>53
It'd be better if I didn't flip digits around, and I spelled Jon Machin's name right.
A student was complaining about digital numbers. 'When I take the root of two and then square it again, the result is already inaccurate!'. Overhearing him, Fu-Tzu laughed. 'Here is a sheet of paper. Write down the precise value of the square root of two for me.'