???

[Kate Luu]

Hi all,

does any body know what going on?

float f1 = 0.1f;

float f2 = 0.2f;

f2 - f1 = 0.100000098

if I check the number like this:

if( f2 = = 0.1f )
...............

NEVER WORKED !!!

[Mr.Tickle]

u cant do exact testing on floats can u ?

"Kate Luu" <cq***@yahoo.com> wrote in message
news:eU**************@TK2MSFTNGP09.phx.gbl...

Hi all,

does any body know what going on?

float f1 = 0.1f;

float f2 = 0.2f;

f2 - f1 = 0.100000098

if I check the number like this:

if( f2 = = 0.1f )
..............

NEVER WORKED !!!

[Kate Luu]

When we use the computer, we need the precisely, absolute accuracy, if the
computer wasn't precise as it is, who will use the computer for
calculation???
don't tell me 2+2=5 is OK for you.

so 0.2 - 0.1 should be = 0.1, not 0.1000000098;

For scientific, we need the result must be very accurate.

0.2 - 0.1 is nothing. Do you ever work for government???

"Mr.Tickle" <Mr******@mrmen.com> wrote in message
news:e$**************@TK2MSFTNGP12.phx.gbl...

u cant do exact testing on floats can u ?

"Kate Luu" <cq***@yahoo.com> wrote in message
news:eU**************@TK2MSFTNGP09.phx.gbl...

Hi all,

does any body know what going on?

float f1 = 0.1f;

float f2 = 0.2f;

f2 - f1 = 0.100000098

if I check the number like this:

if( f2 = = 0.1f )
..............

NEVER WORKED !!!

[Tim Mulholland]

If i'm not mistaken, you can't get .1 exactly with floating point numbers
because of the way they are implemented, right?

<quote from http://grouper.ieee.org/groups/754/faq.html>
Binary floating-point numbers consist of signed integers multiplied by
powers of two. When fractional, you can also consider them as integers
divided by powers of two. The decimal number 0.1, or 1/10, is not an integer
over a power of two. The 854 standard encompasses decimal arithmetic, but
there is little hardware support outside of desktop calculators.

</quote>

"Kate Luu" <cq***@yahoo.com> wrote in message
news:uP**************@tk2msftngp13.phx.gbl...

When we use the computer, we need the precisely, absolute accuracy, if the
computer wasn't precise as it is, who will use the computer for
calculation???
don't tell me 2+2=5 is OK for you.

so 0.2 - 0.1 should be = 0.1, not 0.1000000098;

For scientific, we need the result must be very accurate.

0.2 - 0.1 is nothing. Do you ever work for government???

"Mr.Tickle" <Mr******@mrmen.com> wrote in message
news:e$**************@TK2MSFTNGP12.phx.gbl...

u cant do exact testing on floats can u ?

"Kate Luu" <cq***@yahoo.com> wrote in message
news:eU**************@TK2MSFTNGP09.phx.gbl...

Hi all,

does any body know what going on?

float f1 = 0.1f;

float f2 = 0.2f;

f2 - f1 = 0.100000098

if I check the number like this:

if( f2 = = 0.1f )
..............

NEVER WORKED !!!

[Kate Luu]

Thanks you so much, Tickle and Time. I'm very appreciated for you all help.
Have a nice day...

Kate Luu

"Tim Mulholland" <ti*@eyeresponse.com> wrote in message
news:ur**************@TK2MSFTNGP09.phx.gbl...

If i'm not mistaken, you can't get .1 exactly with floating point numbers
because of the way they are implemented, right?

<quote from http://grouper.ieee.org/groups/754/faq.html>
Binary floating-point numbers consist of signed integers multiplied by
powers of two. When fractional, you can also consider them as integers
divided by powers of two. The decimal number 0.1, or 1/10, is not an integer over a power of two. The 854 standard encompasses decimal arithmetic, but
there is little hardware support outside of desktop calculators.

</quote>

"Kate Luu" <cq***@yahoo.com> wrote in message
news:uP**************@tk2msftngp13.phx.gbl...

When we use the computer, we need the precisely, absolute accuracy, if the computer wasn't precise as it is, who will use the computer for
calculation???
don't tell me 2+2=5 is OK for you.

so 0.2 - 0.1 should be = 0.1, not 0.1000000098;

For scientific, we need the result must be very accurate.

0.2 - 0.1 is nothing. Do you ever work for government???

"Mr.Tickle" <Mr******@mrmen.com> wrote in message
news:e$**************@TK2MSFTNGP12.phx.gbl...

u cant do exact testing on floats can u ?

"Kate Luu" <cq***@yahoo.com> wrote in message
news:eU**************@TK2MSFTNGP09.phx.gbl...
> Hi all,
>
> does any body know what going on?
>
> float f1 = 0.1f;
>
> float f2 = 0.2f;
>
> f2 - f1 = 0.100000098
>
> if I check the number like this:
>
> if( f2 = = 0.1f )
> ..............
>
> NEVER WORKED !!!
>
>

[Morten Wennevik]

If only that were true

float isn't very precise, and banks use decimal numbers that are many times
more precise than float, but they aren't very precise either.

I think someone mentioned that rounding 5.555 didn't lead to 5.56 but 5.55,
because the nearest number to 5.555 was in fact
5.554999999999999214916394143 or something. So you can't use exact
comparison for floats.

Try turning it into an int by multiplying the numbers with 10000 or
something and check if (int)(f2*10000) == 1000

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

[Nicole Calinoiu]

Or just use the Decimal type if appropriate...

"Morten Wennevik" <mo************@hotmail.com> wrote in message
news:oprvltw2h3ge0n9a@localhost...

If only that were true

float isn't very precise, and banks use decimal numbers that are many times more precise than float, but they aren't very precise either.

I think someone mentioned that rounding 5.555 didn't lead to 5.56 but 5.55, because the nearest number to 5.555 was in fact
5.554999999999999214916394143 or something. So you can't use exact
comparison for floats.

Try turning it into an int by multiplying the numbers with 10000 or
something and check if (int)(f2*10000) == 1000

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

[Kate Luu]

Thanks you all very much. Have a wonderful day...

Kate

"Nicole Calinoiu" <ni*****@somewhere.net> wrote in message
news:#E**************@TK2MSFTNGP11.phx.gbl...

Or just use the Decimal type if appropriate...

"Morten Wennevik" <mo************@hotmail.com> wrote in message
news:oprvltw2h3ge0n9a@localhost...

If only that were true

float isn't very precise, and banks use decimal numbers that are many

times

more precise than float, but they aren't very precise either.

I think someone mentioned that rounding 5.555 didn't lead to 5.56 but

5.55,

because the nearest number to 5.555 was in fact
5.554999999999999214916394143 or something. So you can't use exact
comparison for floats.

Try turning it into an int by multiplying the numbers with 10000 or
something and check if (int)(f2*10000) == 1000

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

[Jon Skeet]

Kate Luu <cq***@yahoo.com> wrote:

does any body know what going on?

Yup. See http://www.pobox.com/~skeet/csharp/floatingpoint.html

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Ravichandran J.V.]

with regards,
J.V.Ravichandran
- http://www.geocities.com/
jvravichandran
- http://www.411asp.net/func/search?
qry=Ravichandran+J.V.&cob=aspnetpro
- http://www.southasianoutlook.com
- http://www.MSDNAA.Net
- http://www.csharphelp.com
- http://www.poetry.com/Publications/
display.asp?ID=P3966388&BN=999&PN=2
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