# Scalar precision: float vs. double

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 August 25, 2011, 09:35 Scalar precision: float vs. double #1 Senior Member     Hisham Elsafti Join Date: Apr 2011 Location: Braunschweig, Germany Posts: 249 Blog Entries: 10 Rep Power: 9 Hi I use scalars to solve a (simple closed form) quadratic equation. Nevertheless, they always give a 6 digits precision (a float). I tried to declare the scalars as doubleScalar instead of just scalar. However, the result is still in 6 digits. I made sure that the solution can be more precise http://www.mathsisfun.com/quadratic-...on-solver.html

 August 25, 2011, 09:51 #2 Senior Member   Felix L. Join Date: Feb 2010 Location: Hamburg Posts: 165 Rep Power: 10 This is probably an output related issue. How are you printing out your results? Greetings, Felix

August 25, 2011, 09:56
#3
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Hisham Elsafti
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I use the following

Quote:
 #include "IOstreams.H" using namespace Foam Info << scalar;

August 25, 2011, 10:24
#4
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Hisham Elsafti
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Thanks for the tip. I guess it is an output issue. So using "cout" one can use:

Quote:
 cout.precision(15);
Is there a possible way around for "Info" just for debugging sake. Anyway thanks a lot for quick answer.

Vielen Dank nochmal

 August 25, 2011, 11:09 #5 Senior Member   David Gaden Join Date: Apr 2009 Location: Winnipeg, Canada Posts: 436 Rep Power: 14 There's a couple of precision options in the controlDict. One is for the time directory name, and the other is for the output. Can't remember what they are off-hand, but they should be easy to find.

August 25, 2011, 11:24
#6
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Hisham Elsafti
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Hi marupio

Thanks a lot, I found it:

Quote:
 writePrecision 15;

 Tags double, float, scalar

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