QCalc is a free, open-source Modelica library to represent quantities using various units, including but not limited to SI. The approach is based on quantity calculus (hence the name "QCalc").

QCalc can be used like this:

import Q = QCalc.Quantities; import U = QCalc.Units; Q.Pressure p = U.atm + 50*U.Pa;

Nonscalar units such as degree Celsius
and decibel are also supported.
The `*`

and `/`

operators are overloaded
to call the unit's transformation (*number* ↦ *quantity*) and its inverse, respectively.
For example, this will give a value of *x* = 100:

Real x = (0*U.degC + 100*U.K)/U.degC;

and this will too:

Real x = (10/U.dB + 10/U.dB)*U.dB;

since we have multiplied the numbers by adding their logarithms.

The quantities are not directly compatible with the Modelica Standard Library (MSL) since MSL expresses quantities in SI units. To convert between QCalc and MSL, create an adapter with equations like this:

p = p_SI*U.Pa;

where `p`

is pressure as a quantity (in QCalc), `p_SI`

is pressure in
pascal (in MSL), and `U.Pa`

is
the pascal from QCalc.Units.

Please see the getting started page for more information. If you wish to use the same approach with Modelica results in Python, please see ModelicaRes and natu.

**Licensed by the Hawaii Natural Energy Institute under the Modelica License 2**

Copyright © 2009–2014,
Hawaii Natural Energy Institute and
Georgia Tech Research Corporation.

*This Modelica package is free software and the use is completely
at your own risk; it can be redistributed and/or modified under the
terms of the Modelica License 2. For license conditions (including the
disclaimer of warranty) see
QCalc.UsersGuide.License
or visit http://www.modelica.org/licenses/ModelicaLicense2.*

Name | Description |
---|---|

UsersGuide | User's Guide |

Blocks | Input/output blocks to convert units |

Units | Constants and units of physical measure |

Quantities | Types to represent physical values |

Math | Library of mathematical functions (e.g., sin, cos), where angle is a quantity |

Icons | Package of icons |

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