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I don't get this.

 
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I don't get this., log 10
Ephemeralz
14 Oct, 2008 - 11:16 PM
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I'm supposed to write a class, where one of the instance variable is the distance of a star. Here's what it says in the question: The instance variable logdist is distance (taking log10) in meters.

When I print it out, its supposed to be something like 9.19e+17 meters. The question says: When you print it out, ypu need to use the Math class because distance are given in logarithmic(log base 10) scale.

I don't get what the question is saying!

I know for sure 9.19e+17 means 9.19*10 to the power of 17, but what should I use for the instance variable?

I'm not looking for a code or something, just an example of what value I should put in the instance variable part.
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g00se
RE: I Don't Get This.
15 Oct, 2008 - 12:19 AM
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You need something like the following ('distance' would be the 'raw' distance):

CODE

public double getDistance() {
    return Math.log10(distance);
}
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Ephemeralz
RE: I Don't Get This.
15 Oct, 2008 - 12:40 AM
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QUOTE(g00se @ 15 Oct, 2008 - 01:19 AM) *

You need something like the following ('distance' would be the 'raw' distance):

CODE

public double getDistance() {
    return Math.log10(distance);
}



So you mean my value for logdist will be something like 8674832423.34 meters, and my result is log10(8674832423.34)?

But the qn said that the printed value will be 9.17e+17!

Sorry, but I still don't get it! =(
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g00se
RE: I Don't Get This.
15 Oct, 2008 - 12:57 AM
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Sorry. Misread it I think. All you need, I think, is something like:

CODE

double actualDist = Math.pow(10, logDist);


If you take, for logDist, something like 17.962369335670022, you will see a value something like your tutor mentioned for 'actualDist'
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Ephemeralz
RE: I Don't Get This.
15 Oct, 2008 - 10:41 AM
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QUOTE(g00se @ 15 Oct, 2008 - 01:57 AM) *

Sorry. Misread it I think. All you need, I think, is something like:

CODE

double actualDist = Math.pow(10, logDist);


If you take, for logDist, something like 17.962369335670022, you will see a value something like your tutor mentioned for 'actualDist'


Hmm, meaning if my distance is 9.19*10^17 meters, my code will be like this?

CODE


private double logdist = 17.962369

public double getlogdist()
{
      return Math.pow(10, logdist)
}
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g00se
RE: I Don't Get This.
15 Oct, 2008 - 10:47 AM
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Not quite. getlogdist() should be getDistance() since you're returning the actual distance
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Ephemeralz
RE: I Don't Get This.
15 Oct, 2008 - 07:41 PM
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Alright thanks, that sounds right.
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