Java Utililty Methods Factorial

List of utility methods to do Factorial

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Description

The list of methods to do Factorial are organized into topic(s).

Method

longfactorial(long n)
This function computes the factorial of an long integer 
long fac = 1;
if (n < 0) {
    throw new RuntimeException("Underflow error in factorial");
} else if (n > 20) {
    throw new RuntimeException("Overflow error in factorial");
} else if (n == 0) {
    return 1;
} else {
...
longfactorial(long num)
Gets the factorial of a number 
if (num == 0)
    return 1;
if (num == 2 || num == 1) {
    return num;
} else {
    return num * factorial(num - 1);
doublefactorialAsDouble(int n)
factorial As Double 
double result = 1;
for (int i = 1; i <= n; i++) {
    result *= (double) i;
return result;
doublefactorialAsDoubleIncludeDivisor(int n, double divisor)
Computes n! 
double result = 1.0 / divisor;
for (int i = 1; i <= n; i++) {
    result *= (double) i;
return result;
intfactorialCheckBounds(int n)
Compute n! 
long result = 1;
for (int i = 1; i <= n; i++) {
    result *= (long) i;
    if (result > Integer.MAX_VALUE) {
        throw new Exception("n! causes integer overflow");
return (int) result;
...
doublefactorialDouble(final int n)
Returns n!. 
if (n < 0) {
    throw new IllegalArgumentException("must have n >= 0 for n!");
return Math.floor(Math.exp(factorialLog(n)) + 0.5);
doublefactorialLog(final int n)
Returns the natural logarithm of n!. 
if (n < 0) {
    throw new IllegalArgumentException("must have n > 0 for n!");
double logSum = 0;
for (int i = 2; i <= n; i++) {
    logSum += Math.log((double) i);
return logSum;
...
doublefactorialLog(final int n)
Returns the natural logarithm of n!. 
if (n < 0) {
    return 0;
if (n < 21) {
    return Math.log(factorial(n));
double logSum = 0;
for (int i = 2; i <= n; i++) {
...