diff --git a/misc/Fibonacci_fast.c b/misc/Fibonacci_fast.c index becb8c880..4db1b4b84 100644 --- a/misc/Fibonacci_fast.c +++ b/misc/Fibonacci_fast.c @@ -1,76 +1,81 @@ /** - @file Fibonacci_fast.c - @author: Krishna Vedala + @file + @author Krishna Vedala @date 2 October, 2019 @brief Compute \f$m^{mth}\f$ Fibonacci number using the formulae: \f{eqnarray*}{ - F_{2n-1} &=& F_n^2 + F_{n-1}^2 \\ + F_{2n-1} &=& F_n^2 + F_{n-1}^2 \\ F_{2n} &=& F_n\left(2F_{n-1} + F_n\right) \f} */ -#include -#include -#include +#include +#include +#include /** Returns the \f$n^{th}\f$ and \f$n+1^{th}\f$ Fibonacci number. The return variables are C & D respectively. */ -void fib(unsigned long n, unsigned long *C, unsigned long *D) -{ - //Out of Range checking - if(n < 0){ +void fib(unsigned long n, unsigned long *C, unsigned long *D) +{ + //Out of Range checking + if (n < 0) + { printf("\nNo Such term !\n"); exit(0); } - + unsigned long a, b, c, d; - + if (n == 0) { C[0] = 0; - if(D) + if (D) D[0] = 1; return; } - fib(n >> 1, &c, &d); /**< Compute F(n/2) */ + fib(n >> 1, &c, &d); /* Compute F(n/2) */ a = c * ((d << 1) - c); b = c * c + d * d; - if (n % 2 == 0) /**< If n is even */ + if (n % 2 == 0) /* If n is even */ { C[0] = a; - if(D) + if (D) D[0] = b; return; } - + /**< If n is odd */ C[0] = b; - if(D) + if (D) D[0] = a + b; return; -} - +} + +/** + * main function + */ int main(int argc, char *argv[]) { - unsigned long number, result; - - setlocale(LC_NUMERIC, ""); // format the printf output + unsigned long number, result; - //Asks for the number/position of term in Fibonnacci sequence + setlocale(LC_NUMERIC, ""); // format the printf output + + //Asks for the number/position of term in Fibonnacci sequence if (argc == 2) number = atoi(argv[1]); - else { + else + { printf("Enter the value of n(n starts from 0 ): "); scanf("%lu", &number); } - + fib(number, &result, NULL); - - printf("The nth term is : %'lu \n", result); - - return 0; + + printf("The nth term is : %'lu \n", result); + + return 0; } \ No newline at end of file