CH12
....\DirectionalDerivative.m
....\Direction_Cosine.m
....\Extremum2.m
....\Least_square.m
....\max_min.m
....\mtaylor.m
....\PartialDerivative.m
....\reshapefile.m
....\TangentNormPlane.m
....\TangentPlaneNormLine.m