.. _ikin_extension:

ikin (extension)
------------------------------------------
This function returns the joint position, among the 8 joint configurations, that corresponds to iSolutionSpace and is equivalent to the robot pose in task space.

**Definition** |br|
``DRFLEx.h`` within class `CDRFLEx`, public section

.. code-block:: cpp

    LPINVERSE_KINEMATIC_RESPONSE ikin(
        float fSourcePos[NUM_TASK],
        unsigned char iSolutionSpace,
        COORDINATE_SYSTEM eTargetRef,
        unsigned char iRefPosOpt
    ) {
        return _ikin_ex(_rbtCtrl, fSourcePos, iSolutionSpace, eTargetRef, iRefPosOpt);
    };

**Parameter**

.. list-table::
   :widths: 18 18 18 46
   :header-rows: 1

   * - **Parameter Name**
     - **Data Type**
     - **Default Value**
     - **Description**
   * - fSourcePos
     - float[6]
     - -
     - Target task location for six axes (TCP pose to be solved for).
   * - iSolutionSpace
     - unsigned char
     - -
     - Solution space index (0-7) selecting one of eight IK configurations, or 255 to let the controller choose the reachable solution.
   * - eTargetRef
     - :ref:`COORDINATE_SYSTEM <enum_coordinate_system>`
     - -
     - Reference coordinate system for the TCP.
   * - iRefPosOpt
     - unsigned char
     - -
     - Reference pose option. The function does not send this value to the controller, so every value gives the same result.

**Return**

.. list-table::
   :widths: 25 75
   :header-rows: 1

   * - **Value**
     - **Description**
   * - :ref:`LPINVERSE_KINEMATIC_RESPONSE <struct_inverse_kinematic_response>`
     - Extended inverse-kinematics response including the solved joint position (and related metadata).

.. note::

   This call waits for the controller to answer.

   The returned pointer refers to storage in the CDRFLEx object that other DRFL calls and every reconnect reuse; copy the structure before making another DRFL call. The 3-argument ``ikin`` returns its result in storage shared by all CDRFLEx objects in the process instead; see :ref:`ikin <ikin>`. Except for ``get_user_home``, the pointer is never NULL; do not use a NULL check to detect failure.

**Example**

.. code-block:: cpp

   float x6[6] = { 370.9f, 719.7f, 651.5f, 90.f, -180.f, 0.f };
   LPINVERSE_KINEMATIC_RESPONSE res = drfl.ikin(x6, 2, COORDINATE_SYSTEM_BASE, (unsigned char)0);

   float q[6] = {0};
   for (int i = 0; i < 6; ++i) {
       q[i] = res->_fTargetPos[i];   // copy solved joints
   }
   drfl.movej(q, 60, 30);

This example solves IK for the TCP pose `x6` in the **BASE** frame with **solution space = 2** and **ref-pose option = 0**.  
The solved joint values are copied from `res->_fTargetPos` into `q`, then executed via `movej(q, 60, 30)` (velocity 60, acceleration 30).  
Use different solution spaces (0-7) to select another valid joint configuration for the same TCP pose.