User Guide

Performing Computations
You can use constant values in any computation. To use constant values
with units, use a Units environment as described in Performing Computations
with Units (page 102). For information on computing with quantities that
have an uncertainty, see the following section.
Modification and Extensibility
You can change the definition of a scientific constant or element (or isotope)
property.
For more information, refer to the ?ScientificConstants[ModifyConstant]
and ?ScientificConstants[ModifyElement] help pages.
You can extend the set of:
• Constants
• Elements (and isotopes)
• Element (or isotope) properties
For more information, refer to the ?ScientificConstants[AddConstant],
?ScientificConstants[AddElement], and ?ScientificConstants[AddProp-
erty] help pages.
For more information about constants, refer to the ?ScientificConstants
help page.
Uncertainty Propagation
Some computations involve uncertainties (or errors). Using the ScientificEr-
rorAnalysis package, you can propagate the uncertainty in these values
through the computation to indicate the possible error in the final result.
The ScientificErrorAnalysis package does not perform interval arithmetic.
That is, the error of an object does not represent an interval in which possible
values must be contained. (To perform interval arithmetic, use the Tolerances
package. For more information, refer to the ?Tolerances help page.) The
3.5 Units, Scientific Constants, and Uncertainty • 111