double subtraction

[Tony Stoyle]

Does anyone know what on earth is going on here? This code is inside a JSP page but I guess that is academic -
double f1 = 569.56;
double f2 = 316.505;
double f3 = f1 - f2;
The result should be 253.055 but is coming out as 253.05499999999995 .............
Any advice appreciated before I go mad! Thanks.

[Wilfried LAURENT]

Hi,
There have been several threads on the same topics. See for example:

thread 1
thread 2
W.

[Dirk Schreckmann]

This past conversations in the Cattle Drive mentions links that describe well what is going on.

[Thomas Paul]

Blame the IEEE.

[Jamie Robertson]

try using java.math.BigDecimal using a String as a constructor. For some reason it keeps the correct precision.

double f1 = 569.56;
double f2 = 316.505;
BigDecimal b1 = new BigDecimal( Double.toString( f1 ) );
BigDecimal b2 = new BigDecimal( Double.toString( f2 ) );
BigDecimal b3 = b1.subtract( b2 );
System.out.println( "The result is " + b3.toString() );

output:
The result is 253.055
Not exactly what I call efficient though!
Jamie

[Tony Stoyle]

Many thanks for your replies..