number lenght

Hi. I have code like so:double a= 1.11111111111111111111111111111111111111111111111111;System.out.println(a);And it writes 1.11111111111111112. Why? What should I do to write pi const. (but not from string)?

[268 byte] By [laqa] at [2007-11-27 2:24:12]

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# 1

This is related to the way doubles are stored internally.

It's technically impossible to represent the number

1.11111111111111111111111111111111111111111111111111

exactly using the IEEE floating point number binary format. So you don't actually have

1.111111111111111111111111111111111111111111111111111

stored. The other problem is that the jvm will round your output to a certain number of decimal places when you want to display it, so you will need to use a formatter to specify how many decimal places you really want. That still won't guarantee that it wont round the last digit up to a 2, though, because of what I said above.

- Adam

guitar_man_Fa at 2007-7-12 2:30:54 >

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# 2

so what should I do if I want to compute pi const and display e.g. 70 digit after comma?

laqa at 2007-7-12 2:30:54 >

# 3

If you want Pi then take a look at the Math class. It is in java.lang package so no need to import anything.

floundera at 2007-7-12 2:30:54 >

# 4

Use the java.math.BigDecimal class.- Adam

guitar_man_Fa at 2007-7-12 2:30:54 >

# 5

> If you want Pi then take a look at the Math class. It> is in java.lang package so no need to import anything.? to 70 significant figures? I doubt it, but maybe.

guitar_man_Fa at 2007-7-12 2:30:54 >

# 6

> so what should I do if I want to compute pi const and> display e.g. 70 digit after comma?Trick question?

DrLaszloJamfa at 2007-7-12 2:30:54 >

# 7

> > so what should I do if I want to compute pi const> and> > display e.g. 70 digit after comma?> > Trick question?maybe he's French?

guitar_man_Fa at 2007-7-12 2:30:54 >

# 8

> so what should I do if I want to compute pi const and> display e.g. 70 digit after comma?Use the BigDecimal class to do that computation.

DrClapa at 2007-7-12 2:30:54 >

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