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Pascal/Delphi Source File  |  1985-05-17  |  1.8 KB  |  33 lines
  1. (*--------------------------------------------------------------------------*)
  2. (*                   LogTen --- Calculate base 10 logarithm                 *)
  3. (*--------------------------------------------------------------------------*)
  4.  
  5. FUNCTION LogTen( X: REAL ) : REAL;
  6.  
  7. (*--------------------------------------------------------------------------*)
  8. (*                                                                          *)
  9. (*     Function:  LogTen                                                    *)
  10. (*                                                                          *)
  11. (*     Purpose:   Calculates base ten logarithm                             *)
  12. (*                                                                          *)
  13. (*     Calling Sequence:                                                    *)
  14. (*                                                                          *)
  15. (*        Logval := LogTen( X: REAL ) : REAL;                               *)
  16. (*                                                                          *)
  17. (*           X      --- value to find logarithm of                          *)
  18. (*                                                                          *)
  19. (*           Logval --- resultant logarithm (X > 0);                        *)
  20. (*                      = 0 if X <= 0.                                      *)
  21. (*                                                                          *)
  22. (*     Calls:  LN                                                           *)
  23. (*                                                                          *)
  24. (*--------------------------------------------------------------------------*)
  25.  
  26. BEGIN (* LogTen *)
  27.  
  28.    IF X <= 0.0 THEN
  29.       LogTen := 0.0
  30.    ELSE
  31.       LogTen := LN( X ) * LNTenInv;
  32.  
  33. END   (* LogTen *);