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Thread: converting a decimal to an int
 10122009, 08:15 AM #1Member
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converting a decimal to an int
Hi, good to be here.
I am writing a program that simulates a projectile's trajectory. I have the mathematical equation to do so but I have a problem when I try to implement graphics.
The problem is that when I compute the math the resulting X and Y coordanints of the projectile ends up in a long decimal..
for example the X coordanint might be 9.2938 and the Y coordanint might be 17.3726.
The graphical framework I'm using only excepts integers when drawing objects to the screen so I can't use the exact position of the X and Y coordanints. This model does not have to be extremely accurate so I figure the easy way to solve this problem is to round the number with "Math.round()" function.
This is math equation I'm trying to round...
yPos = Math.round((startHeight + velocity * Math.sin(angle) * time  gravity * time * time/2));
xPos = Math.round((startLength + velocity * Math.cos(angle) * time));
when I try to do this I get an error saying, "Possible loss of precision. found: long, required: int"
All the variables in this equation are type "double", and the xPos and Ypos variables are type int...
Can someon please enlighten me on the situation?
 10122009, 08:25 AM #2Senior Member
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 10122009, 08:26 AM #3Senior Member
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If accuracy is not a problem, why not just
Java Code:double d = 5.43764826; int i = (int) d;
Java Code:double d = 5.43764826; int i = (int) (d + 0.5);
Last edited by masijade; 10122009 at 08:30 AM.
 10122009, 08:31 AM #4Senior Member
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 10122009, 08:34 AM #5Senior Member
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Using "your" code
Simply rounding everything down
Java Code:yPos = (int) (startHeight + velocity * Math.sin(angle) * time  gravity * time * time/2); xPos = (int) (startLength + velocity * Math.cos(angle) * time);
Java Code:yPos = (int) ((startHeight + velocity * Math.sin(angle) * time  gravity * time * time/2) + 0.5); xPos = (int) ((startLength + velocity * Math.cos(angle) * time) + 0.5);
 10122009, 08:46 AM #6Member
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Thanks both of you for the advice. I will try casting it as an int. I will post the results when I get it done. Hopefully it works
 10122009, 09:05 AM #7Member
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Worked great!! thanks. Such a simple solution, I'm embarrassed I didnt try that before :p
 10122009, 09:26 AM #8Senior Member
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 10122009, 09:32 AM #9Member
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Huh?? what is a defenestration time?
 10122009, 09:41 AM #10Senior Member
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Defenestration  Wikipedia, the free encyclopedia
Watch out for the lacerations when your turn comes.
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