Arbitrary-precision arithmetic in ColdFusion?

<!---

Calculate 100 factorial using exclusively numbers of
type BigDecimal. Then all significant figures count.

--->

<cfscript>

/* the double 1.0 as BigDecimal*/
factorial = createobject("java","java.math.BigDecimal").init(1.0);

/* 100 factorial = 1x2x3x ... x100, but then in BigDecimals.*/
for ( i = 2; i LTE 100; i = i+1) {
    iObj = createobject("java","java.math.BigDecimal").init(tostring(i));
    factorial = factorial.multiply(iObj);
}

/* Make Coldfusion store result as string, avoiding
truncation and scientific notation */
result = factorial.toPlainString();

// extract and display the integer part
writeoutput(listGetAt(result,1,"."));
</cfscript>

It's probably worth while reading up on the sizes of various numeric datatypes in Java, and how floating point numbers work.

Java (and, accordingly CF), is unlikely to be able to represent that number ot the accuracy you need it to.

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Long.html

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Double.html

http://java.sun.com/j2se/1.4.2/docs/api/java/math/BigDecimal.html (which is what PrecisionEvaluate() uses)

http://en.wikipedia.org/wiki/Floating_point

To do what you need to do, you're going to have to write your own algorithm to represent numbers that long (as a string that you build up), or look around to see if someone else has already done it, and re-implement to fulfil your own requirements.

--

Adam

Try numberformat()