SUBROUTINE PTSKMC(X,Y,XO,YO,PHIO,ELAMO,A,B,PSK,MC,KO)                     
C                                                                               
C        THIS SUBROUTINE WILL COMPUTE THE POINT SCALE FACTOR AND THE MERIDIAN   
C      CONVERGENCE FOR THE DOUBLE STEREOGRAPHIC PROJECTION.                     
C                                                                               
C        INPUT:                                                                 
C              X,Y - COORDINATES OF THE POINT (IN METRES).                      
C              XO,YO - COORDINATES OF THE ORIGIN (IN METRES).                   
C              PHIO,ELAMO - PHI AND LAMDA OF THE ORIGIN (IN RADIANS).           
C              A,B - SEMI-MAJOR AND SEMI-MINOR AXES OF THE ELLIPSOID (IN METRES)
C                                                                               
C        OUTPUT:                                                                
C              PSK - POINT SCALE FACTOR.                                        
C              MC - MERIDIAN CONVERGENCE (IN RADIANS).                          
C                                      WRITTEN BY G.BOWIE, JAN. 1977.           
C                                      WRITTEN BY G.BOWIE, JAN. 1978.           
C                                                                               
      IMPLICIT REAL*8(A-Z)                                                      
      CALL STGINL(PHIO,ELAMO,A,B,R,C1,C2,E,CHIO,SLAMO)                          
      CALL PLTSP(X,Y,XO,YO,KO,R,CHIO,SLAMO,CHI,SLAM)                            
      CALL SPTEL(CHI,SLAM,C1,C2,E,PHI,ELAM)                                     
      WRITE(6,*)PHIO,ELAMO,CHIO,SLAMO,CHI,SLAM                                  
      WRITE(6,*)XO,YO,X,Y,KO,R                                                  
      CC=DCOS(CHI)                                                              
      CP=DCOS(PHI)                                                              
      CCO=DCOS(CHIO)                                                            
      CDL=DCOS(SLAM-SLAMO)                                                      
      SC=DSIN(CHI)                                                              
      SP=DSIN(PHI)                                                              
      SDL=DSIN(SLAM-SLAMO)                                                      
      SCO=DSIN(CHIO)                                                            
      N=A/DSQRT(1.D0-E**2*SP**2)                                                
      PSK=2.D0*C1*R*CC/(N*CP*(1.D0+SCO*SC+CCO*CC*CDL))                          
      NUM=SDL*(SC+SCO)                                                          
      DEN=CC*CCO+(1.D0+SC*SCO)*CDL                                              
      MC=DATAN2(NUM,DEN)                                                        
      RETURN                                                                    
      END