  We calculate the metric and affine connection due to a piecewise linear
cosmic string loop, and the effect of gravitational back reaction for the
Garfinkle-Vachaspati loop with four straight segments. As expected, back
reaction reduces the size of the loop, in accord with the energy going into
gravitational waves. The "square" (maximally symmetric) loop evaporates without
changing shape, but for all other loops in this class, the kinks become less
sharp and segments between kinks become curved. If the loop is close to the
square case, it will evaporate before its kinks are significantly changed, if
it is far from square, the opening out of the kinks is much faster than
evaporation of the loop.
