Parameter

Values

Description

CSTOL

<Real>

Default = 3.5

PARAM, CSTOL relates to the FastFRS interface.

If the low rank representation is not selected, then a cancellation tolerance must be provided. The CSTOL value specifies how many decimal digits may be lost to cancellation in one operation during the eigensolution process. Since double precision arithmetic maintains nearly 16 digits of precision, the recommended limit of 3.5 on the number of digits lost leaves more than 12 digits, which is quite conservative for maintaining adequate accuracy for engineering purposes. You may choose to increase this value to speed computation, at the risk of introducing inaccuracy from uncorrected cancellation error. Setting it to 16 turns off the capability to address cancellation error in the eigensolution, and this has consistently been found to give very satisfactory results when the number of modes is under three thousand.

Refer to FastFRS Usage (Fast Frequency Response Solver) in the User's Guide for more details.