ERRATA (6 May 1985)
OT REPORT 75-76 
  
A VERSATILE THREE-DIMENSIONAL RAY TRACING COMPUTER PROGRAM
FOR RADIO WAVES IN THE IONOSPHERE 
  
by R. Michael Jones and Judith J. Stephenson 

The 8th line from the bottom of page 9 should read: 
    (1) the dispersion relation cannot be exactly satisfied, or

The first line in the 3rd complete paragraph on page 12 should read: 
    Similarly, the AHWFNC (Appleton-Hartree, with field, no colli-

Line BACK052 in SUBROUTINE BACK UP on page 75 should be replaced by:
      H=R(1)-EARTHR                                                     BACK0519
      STEP=(-R(4)-SQRT(R(4)**2-2.*(H-HS)*R(4)/DRDT(1)*DRDT(4)))/DRDT(4) BACK052

Line BACK060 in SUBROUTINE BACK UP on page 75 should read:
      IF(ABS(R(1)-EARTHR-HS).LT..5E-4.AND.ABS(STEP).LT.1.) GO TO 50     BACK060

Line PRIN008 in SUBROUTINE PRINTR on page 78 should read:
     1      LPOLAR(2),SGN                                               PRIN008

Line PRIN125 in SUBROUTINE PRINTR on page 80 should read: 
      RANGE=EARTHR*ATAN2(RCE,EARTHR+EPS+XMTRH)                          PRIN125 

Following line WFWC006 in SUBROUTINE AHWFWC on page 93, insert the line:
     2      ,SGN                                                        WFWC0065

Line BQNC020 in SUBROUTINE BQWFNC on page 100 should read: 
      REAL N2,NNP,LPOLAR,LPOLRI,KR,KTH,KPH,K2,KDOTY,K4,KDOTY2,          BQNC020 

Line TABX064 in SUBROUTINE TABLEX on page 112 should read: 
      PXPR=PXPTH=PXPPH=0.                                               TABX064 

Following line CHAP024 in SUBROUTINE CHAPX on page 116, insert the line: 
      PXPPH=0.                                                          CHAP0245

Line VCHA010 in SUBROUTINE VCHAPX on page 117 should read: 
      X=PXPR=PXPTH=PXPPH=0.                                             VCHA010 

Line DCHA013 in SUBROUTINE DCHAPT on page 119 should be replaced by:
      HMAX1=HM1+EARTHE*THETA2                                           DCHA013 
      HMAX2=HM2+EARTHE*THETA2                                           DCHA0131
      HMAX=HMAX1                                                        DCHA0132
      IF(FC2.GT.FC1.OR.FC2.EQ.FC1.AND.HMAX2.GT.HMAX1) HMAX=HMAX2        DCHA0133

Line DCHA014 in SUBROUTINE DCHAPT on page 119 should read: 
      X=PXPR=PXPTH=PXPPH=0.                                             DCHA014 

Line DCHA017 in SUBROUTINE DCHAPT on page 119 should read:
      Z1=(H-HMAX1)/SH1                                                  DCHA017

Line LINE013 in SUBROUTINE LINEAR on page 120 should read: 
      X=PXPR=PXPTH=PXPPH=0.                                             LINE013 

Line PARA012 in SUBROUTINE QPARAB on page 121 should read: 
      X=PXPR=PXPTH=PXPPH=0.                                             PARA012 

Following line BULG038 in SUBROUTINE BULGE on page 123, insert the line:
      PXPPH=0.                                                          BULG0385

Following line EXPX014 in SUBROUTINE EXPX on page 124, insert the line: 
      PXPTH=PXPPH=0.                                                    EXPX0145
 
The equation for the gyrofrequency near the top of page 143 should read: 

                       3          2  1/2
    F = F  (R /(R + h)) (1 + 3 cos é)
     H   H   0   0      
          0

    where é is the geomagnetic colatitude.

Line TABZ015 in SUBROUTINE TABLEZ on page 153 should read: 
      IF (READNU.EQ.0.) GO TO 10                                        TABZ015