I found this program that calculates the value of pi somewhere on the net:

Output:Code:#include <stdio.h> #define SCALE 10000 #define MAXARR 2800 #define ARRINIT 2000 main() { int i, j; int carry = 0; int arr[MAXARR+1]; for (i = 0; i <= MAXARR; ++i) arr[i] = ARRINIT; for (i = MAXARR; i; i -= 14) { int sum = 0; for (j = i; j > 0; --j) { sum = sum*j + SCALE*arr[j]; arr[j] = sum % (j*2-1); sum /= (j*2-1); } printf("%04d", carry + sum/SCALE); carry = sum % SCALE; } }

Can someone explain what's happening here and why it works?Code:31415926535897932384626433832795028841971693993751058209749445923078164062862089 98628034825342117067982148086513282306647093844609550582231725359408128481117450 28410270193852110555964462294895493038196442881097566593344612847564823378678316 52712019091456485669234603486104543266482133936072602491412737245870066063155881 74881520920962829254091715364367892590360011330530548820466521384146951941511609 43305727036575959195309218611738193261179310511854807446237996274956735188575272 48912279381830119491298336733624406566430860213949463952247371907021798609437027 70539217176293176752384674818467669405132000568127145263560827785771342757789609 17363717872146844090122495343014654958537105079227968925892354201995611212902196 08640344181598136297747713099605187072113499999983729780499510597317328160963185