.. _method-nl2sol-singular_conv_tol:

"""""""""""""""""
singular_conv_tol
"""""""""""""""""


Singular convergence tolerance


.. toctree::
   :hidden:
   :maxdepth: 1



**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* -1. (use NL2SOL internal default)


**Description**


``singular_conv_tol``
(NL2SOL's ``sctol``) is the singular convergence tolerance, which works
in conjunction with :dakkw:`method-nl2sol-singular_radius` to test for
underdetermined least-squares problems (stop when the relative
reduction yet possible in the sum of squares appears less then
``singular_conv_tol`` for steps of scaled length at most :dakkw:`method-nl2sol-singular_radius`).

The internal default is a function of machine epsilon
(as limited by ``function_precision``). The default is selected with a value of -1.


