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{new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} Software performs computation with 16 digits of accuracy, some of which may be lost when analysis involves systems of significantly different stiffness, where lower-order values are truncated to suit operations with higher-order values. When *lost accuracy* occurs, a warning message reports the location of the occurrence such that users may edit the model if necessary.
Some situations where numerical instability may occur include:
* When [frame|kb:Frame] objects of significantly different stiffness connect at a common [joint|kb:Joint].
* When the rigid-diaphragm assumption is applied to a slab with flexible interconnecting objects.
* When multiple releases are assigned to a joint, causing joint DOF to become orphaned (without stiffness). In this instance, numerical instability warnings indicate a modeling problem which should be corrected.
Depending on the number of digits lost, actions which result include the following:
* *Less than 6* does not generate a response in that values and solution are sufficiently accurate.
* *Between 6 and 11* lost digits of accuracy may or may not create numerical problems, therefore warning message is reported which reads: The results of the analysis may still be acceptable but the user should carefully check the results, especially the global sums of loads.
* *Over 11* digits lost causes analysis to terminate because results may not be sufficiently accurate. The location of the numerical problem is indicated, and a warning message is presented which prompts the user to check and revise the model.
h1. See Also
* [Numerical problems FAQ|kb:Numerical problems FAQ] |
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