.. role:: blue
   :class: blue

.. role:: bfit
   :class: bfit

Two-Dimensional Line MbLine
===========================
.. _MbLine_Two-Dimensional_Straight_Line_:

.. kernel version: 118061

The :blue:`MbLine` class is declared in the *cur_line.h* file.

The two-dimensional straight line :blue:`MbLine` is defined by the start point
:blue:`MbCartPoint` **origin** and the direction vector
:blue:`MbDirection` **direction**:

.. figure:: /MODELER/TWO-DIMENSIONAL_CURVES/pictures/O.3.2.1.png
   :width: 12cm
   :align: center

In the :blue:`PointOn`\( double & *t*,
:blue:`MbCartPoint` & :blue:`r`) method the radius vector of the line
:blue:`r` is described by the vector function

.. math::
   \mathbf{r}(t) = \mathbf{origin} + t \cdot \mathbf{direction}.

The straight line behaves as an infinite object although its data
has boundary values of the parameter *t*\ :subscript:`min` and
*t*\ :subscript:`max`. Note that unlike other curves, in the methods
for calculating the radius vector and its derivatives the line does not adjust
the parameter *t* when it goes beyond the limit values
*t*\ :subscript:`min` and *t*\ :subscript:`max`.