def distance_matrix(client, locations, profile='driving-car', sources=None,
    destinations=None, metrics=None, resolve_locations=None, units=None,
    optimized=None, validate=True, dry_run=None):
    """ Gets travel distance and time for a matrix of origins and destinations.

    :param locations: One or more pairs of lng/lat values.
    :type locations: a single location, or a list of locations, where a
        location is a list or tuple of lng,lat values

    :param profile: Specifies the mode of transport to use when calculating
        directions. One of ["driving-car", "driving-hgv", "foot-walking",
        "foot-hiking", "cycling-regular", "cycling-road",
        "cycling-safe", "cycling-mountain", "cycling-tour", 
        "cycling-electric",]. Default "driving-car".
    :type profile: string

    :param sources: A list of indices that refer to the list of locations
        (starting with 0). If not passed, all indices are considered.
    :type sources: list or tuple

    :param destinations: A list of indices that refer to the list of locations
        (starting with 0). If not passed, all indices are considered.
    :type destinations: list or tuple

    :param metrics: Specifies a list of returned metrics. One or more of ["distance",
        "duration"]. Default ['duration'].
    :type metrics: list of strings

    :param resolve_locations: Specifies whether given locations are resolved or
        not. If set 'true', every element in destinations and sources will 
        contain the name element that identifies the name of the closest street.
        Default False.
    :type resolve_locations: boolean

    :param units: Specifies the unit system to use when displaying results.
        One of ["m", "km", "m"]. Default "m".
    :type units: string

    :param optimized: Specifies whether Dijkstra algorithm ('false') or any 
        available technique to speed up shortest-path routing ('true') is used. 
        For normal Dijkstra the number of visited nodes is limited to 100000.
        Default True
    :type optimized: boolean

    :param validate: Specifies whether parameters should be validated before sending the request. Default True.
    :type validate: bool
    
    :param dry_run: Print URL and parameters without sending the request.
    :param dry_run: boolean
    
    :raises ValueError: When profile parameter has wrong value.
    
    :rtype: call to Client.request()
    """
    params = {'locations': locations}
    if sources:
        params['sources'] = sources
    if destinations:
        params['destinations'] = destinations
    if profile:
        params['profile'] = profile
    if sources:
        params['sources'] = sources
    if destinations:
        params['destinations'] = destinations
    if metrics:
        params['metrics'] = metrics
    if resolve_locations is not None:
        params['resolve_locations'] = resolve_locations
    if units:
        params['units'] = units
    if optimized is not None:
        params['optimized'] = optimized
    return client.request('/v2/matrix/' + profile + '/json', {}, post_json=
        params, dry_run=dry_run)
