from . cimport _mcp
from libc.math cimport fabs


cdef class MCP_Diff(_mcp.MCP):
    """MCP_Diff(costs, offsets=None, fully_connected=True)

    Find minimum-difference paths through an n-d costs array.

    See the documentation for MCP for full details. This class differs from
    MCP in that the cost of a path is not simply the sum of the costs along
    that path.

    This class instead assumes that the cost of moving from one point to
    another is the absolute value of the difference in the costs between the
    two points.

    """
    def __init__(self, costs, offsets=None, fully_connected=True):
        """__init__(costs, offsets=None, fully_connected=True)

        See class documentation.
        """
        _mcp.MCP.__init__(self, costs, offsets, fully_connected)
        self.use_start_cost = 0

    cdef _mcp.FLOAT_T _travel_cost(self, _mcp.FLOAT_T old_cost,
                                   _mcp.FLOAT_T new_cost,
                                   _mcp.FLOAT_T offset_length):
        return  fabs(old_cost - new_cost)