Bulk Data Entry Defines the maximum allowed value of the ratio of terms on the diagonal of the stiffness matrix to the corresponding diagonal terms of the triangular factor matrix during decomposition.

Parameter Value Option Description

No default

If the value of the ratio exceeds that specified on PARAM,MAXRATIO, then OptiStruct will:
ERROR (Default)
Terminate the run with an error.
Issue a warning, depending on the value of the Option field.


  1. This parameter is only supported for Linear Static Analysis. It is currently not supported for optimization runs.
  2. It is supported only for BCS solver and SMP runs. DDM is currently not supported.
  3. If PARAM,MAXRATIO is defined, constraint reduction is automatically enforced. If there are any degrees-of-freedom that violate MAXRATIO, then the corresponding Grid and Component ID is printed and OptiStruct terminates with an error or issues a warning.
  4. Additional ways to define MAXRATIO is by using the OptiStruct Configuration file (.cfg) or by using SYSSETTING (MAXRATIO=VALUE,ERROR/WARN). In case all three ways are defined for the same run, the parameter PARAM,MAXRATIO has highest priority. The next highest priority is the SYSSETTING and finally, if both of the above are not defined, the value for MAXRATIO in the OptiStruct Configuration file is used.