.. highlightlang:: us

.. index:: akimaspline

.. _akimaspline:

akimaspline
===========

.. us.tag  akimaspline ENGLISH New320 Interpolation

:ref:`akimaspline` computes an akima spline for a given x- and y-vector.

.. function::  rmXY = akimaspline(rvX, rvY, p, flag)

.. us.return

**Return Value**

The return value *rmXY* is a real matrix with two columns. The first column
contains the x-coordinates of the spline and the second column contains the
y-coordinates of the spline. In case of an error *rmXY* has only one element
with an error number: 

.. list-table::
   :header-rows: 0

   * - 1
     - not enough memory
   * - 2
     - x-coordinates are not strictly increasing
   * - 3
     - less than 3 datapoints specified.

.. us.params

**Parameters**

.. uparam:: rvX

   *rvX* is a real vector with at least 3 elements in increasing order. The values
   must be strictly increasing.

.. uparam:: rvY

   *rvY* is a real vector with at least 3 elememts.

.. uparam:: p

   The meaning of *p* depends on the value of the parameter *flag*

.. uparam:: flag

   *flag* can be one of the following values:

   .. list-table::
      :header-rows: 1

      * - Value
        - Meaning
      * - 1
        - p is the number of x-, y-coordinates calculated.
      * - 2
        - p is the number of x-, y-coordinates calculated. The original
          x-coordinates are added to the total. 
      * - 3 
        - p is a strictly increasing vector of x-coordinates.

.. us.example

**Example**

.. image:: S:/uniplot-obj/images/akimaspline.*

::

   x = [1,3,5,8]
   y = [0,5,8,2]
   h = plot(x,y)
   xy = akimaspline(x,y,50,2)
   plot(xy[;1],xy[;2],h[2])
   xy = fspline(x,y,0,50)
   plot(xy[;1],xy[;2],h[2])

.. seealso::
   :ref:`overview-mathematic`,
   :ref:`fspline`,
   :ref:`pspline`,
   :ref:`rspline`,
   :ref:`interpol`

:sub:`id-867923`