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APPENDIX                                                                473


                                         =  cos +  sin
                                                       0
                                              0
                                         0
                                        = − sin +  cos�              (A.36)
                                         0
                                                       0
                                               0
                                                =  0
                                                0
                                 =  sincos +  sinsin +  cos
                                                  0
                                 0
                                      0
                                                              0
                                 =  coscos +  cossin −  sin�             (A.37)
                                                              0
                                 0
                                                  0
                                      0
                                        = − sin +  cos
                                                       0
                                        0
                                               0
            Note in conclusion that ∇ isn’t a real vector since vectors must have numbers or functions as
            coordinates, but applying it correctly  we can reserve plenty of our precious time for more
            interesting tasks.
            Vector Differential Operators in Cylindrical and Spherical Coordinate System
            The cylindrical and spherical coordinate systems are mostly used in parallel with the Cartesian
            system but not so wide. We tried to avoid them in our book as much as possible because of their
            scary  appearance  and  manipulation  complexity but decided to keep  here  generally  for
            references.
            Cylindrical coordinate system  =   +   +  
                                                0 
                                         0 
                                                      0 
                                               1   
                                       =  0  +  0  +  0             (A.38)
                                                 
                                             1 (  )  1     
                                       ∘  =  +   +                          (A.39)
                                                    
                                    1             1 (  )    �            (A.40)
                          ×   =  �  −  � +  �  −  � +   �  −
                                 0               0             0
                                                 
                                                                2
                                                           2     
                                                         1  
                                              1 
                                                   
                                         2
                                        ∇  =  �  � +  +                      (A.41)
                                                         2
                                                     2    2
                                              2       2  
                            2
                                     2
                                                                                  2
                                                             2
               grad(div) = ∇  =  �∇  −  −  � +  �∇  −  +  � +  ∇ 
                                                                                0
                                                                                    
                                                              
                                  0
                                       
                                                         0
                                                2
                                                                       2
                                           2        2   
            Spherical coordinate system  =   +   +  
                                        0   0   0 
                                                1     1  
                                        =  0  +  0  +  0             (A.42)
                                                  sin 
                                              2
                                          1 (   )  1  (sin  )  1   
                                    ∘  =  +           +                    (A.43)
                                            2    sin    sin 
                           1   (sin  )     1  1     (  )  1 (  )   
                 ×   =  0  �  −  � +  0  �  −  � +  0  �  −  � (A.44)
                          sin        sin         
                                         2       1       1   
                                                                       2
                                       1  ()
                                  2
                                 ∇  =    +        �sin  � +                 (A.45)
                                                                    2
                                                2
                                                                 2
                                          2   sin      sin   2
                                               2   2  (sin )  2   
                                                                 
                                 2
                                          2
                    grad(div) = ∇  =  �∇  −  −     −           �
                                            
                                       0
                                                                      2
                                                     2
                                                  2   sin     sin 
                                               2    2cos  
                                     2
                              + �∇  −   +       −           �
                                 0       2     2       2  2
                                           sin      sin  
                                    2
                              + �∇  −     +  2     +  2cos   �            (A.46)
                                      
                                 0
                                             2
                                          2
                                                            2
                                                              2
                                                  2
                                           sin    sin    sin  
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