I am attempting to Perlize a simple arithmetic expression that returns the pressure of CO2 gas in PSI needed to carbonate beer with a given number of gas volumes at a given temperature.

Volumes and Temperature are both known. So we have an expressions akin to: 

X = 1 + 2^3 + 4*5 - 6*7^8

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The full expression is: 

Pressures=-16.6999-(0.0101059*Temperature)+(0.00116512*(Temperature^2)
+)+(0.1733554*(Temperature)*(Volumes))+(4.24267*(Volumes))-(0.0684226*
+(Volumes^2))

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This works in Excel yielding a pressure of 12.27462975 for a temperature of 40 and 2.5 volumes of CO2. This does not work in Perl.. 

$temp = 40;
$vol = 2.5;
$pressure=(-16.6999)-(0.0101059*$temp)+(0.00116512*($temp^2))+(0.17335
+4*$temp*$vol)+(4.24267*$vol)-(0.0684226*($vol^2));

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Here I get a pressure of 10.88687404 which is definitely wrong. (I am matching values on a known table for testing).

Is this an issue with floating point precision? I couldn't find a floating point module... Please help.

Janitored by Arunbear - added code tags, and changed title from 'Problems with floating point arithmetic. Please Help!'

In reply to Convert arithmetic expression from Excel to Perl syntax by ameyer

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