🚀 go-pugleaf

Dave Frizzell <davef@jtechmed.com> wrote:

>new to java, i have a double that i need to round to the hundredths
>place (0.01).
>
>double examPercent;
>examPercent = (totalGradePoints / max_points)* MAX_PERCENTAGE;
>round (examPercent); //??? this is very wrong
>
>do i want to use round or something else?  could someone be so kind as
>to help me with the correct syntax.
>
>thanks,
>davef

First of all, might I suggest that you always perform your
multiplications before performing division.

totalGradePoints/max_points will probably result in some roundoff or
precision error, which error will then be multiplied by
MAX_PERCENTAGE. This type of error becomes minimized if your change
your statement to  (totalGradePoints*MAX_PERCENTAGE) / max_points

To round to the second decimal you can use:

double examPercent = (double)(Math.round(
totalGradePoints*MAX_PERCENTAGE * 100 / max_points))  / 100;

Note that the following applies to normal "business rules" rounding.
In mathematics, rounding is done a bit differently.  Since the number
0 is not rounded; numbers 1,2,3,4,5 are rounded up, and numbers
6,7,8,9 are rounded down.  Hence one is rounding up 5 times and down 4
times.

To correct this one rounds up or down depending upon whether the
preceding digit was even or odd. (assuming random data).

Rich
----------------------------------------------------------------------
Richard V. Downing              Work email: richard.downing@vsin.com
Senior Software Engineer        Home email: rvd@mindspring.com
VideoConferencing Systems, Inc. Web: http://rvd.home.mindspring.com
Norcross, Ga
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