**NROPT**

**NROPT**,

*Option1*,

*Option2*,

*Optval***Specifies the Newton-Raphson options in a static or full transient
analysis.**MP ME ST <> PRN <> <> <> EM <> <> PP <> EME MFS

*Option1*Option key:

**AUTO ** | — | Let the program choose the option
(default). |

**FULL ** | — | Use full Newton-Raphson. |

**MODI ** | — | Use modified Newton-Raphson. |

**INIT ** | — | Use the previously computed matrix
(initial-stiffness). |

**UNSYM ** | — | Use full Newton-Raphson with
unsymmetric matrices of elements where the unsymmetric option exists. |

*Option2*Option key:

**CRPL ** | — | When applicable in a static creep analysis,
activates modified Newton-Raphson with a creep-ratio limit. Valid only when *Option1* =
AUTO. |

*Optval*Adaptive descent key:

**ON ** | — | Use adaptive descent (default if
frictional contact exists). Explicit ON is valid only if *Option* =
FULL. |

**OFF ** | — | Do not use adaptive descent (default
in all other cases). |

*CRLIMIT* | — | The
creep-ratio limit for use with the modified Newton-Raphson procedure. Typically,
this value should not exceed 0.15. Valid only when *Option1* =
AUTO (default) and *Option2* = CRPL. |

## Notes

The **NROPT** command specifies the Newton-Raphson option used to solve
the nonlinear equations in a static or full transient analysis.

If used within the solution processor, this command is valid only within
the first load step.

The automatic modified Newton-Raphson procedure with creep-ratio limit
control (**NROPT**,AUTO,CRPL,*CRLIMIT*)
applies to static creep analysis only. When the creep ratio is smaller than
value of the creep ratio limit specified, the modified Newton-Raphson procedure
is used. If convergence difficulty occurs during solution, use the full Newton-Raphson
procedure.

The command **NROPT**,UNSYM
is also valid in a linear
non-prestressed modal analysis that is used to perform a brake squeal
analysis. In this special case, the command is used only to generate the unsymmetric
stiffness matrix; no Newton-Raphson iterations are performed.

The default values given for this command assume **SOLCONTROL**,ON
(the default). See the description of **SOLCONTROL** for a
complete listing of the defaults set by **SOLCONTROL**,ON and **SOLCONTROL**,OFF.

See Newton-Raphson
Option in the *Structural Analysis Guide* for more information.

This command is also valid in PREP7.