Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: F-PC Forth Tutorial
Message-ID: <929.UUL1.3#5129@willett.UUCP>
Date: 9 May 90 03:44:59 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 105


 Date: 05-06-90 (23:28)              Number: 3 (Echo)
   To: JACK BROWN                    Refer#: NONE
 From: PAUL BRANNON                    Read: NO
 Subj: L. 3, P. 4 EXERCISES          Status: PUBLIC MESSAGE

 \ exercise 3.9 single number display operator table using BINARY
 : bitable        ( n -- )
         cr 1 spaces
            ."  unsigned " ."    signed " ."          unsigned "
            ."    signed " ."  unsigned " ."    signed "
         cr 1 spaces
            ."   decimal " ."   decimal " ."            binary "
            ."    binary " ."      hex  " ."      hex  "
         20 0 do
                 cr
                 decimal dup 10 u.r
                         dup 10  .r
                 binary  dup 18 u.r
                         dup 10  .r
                 hex     dup 10 u.r
                         dup 10  .r
                 1 + loop drop decimal cr ;

 -9 bitable
   unsigned    signed          unsigned    signed  unsigned    signed
    decimal   decimal            binary    binary      hex       hex
      65527        -9  1111111111110111     -1001      FFF7        -9
      65528        -8  1111111111111000     -1000      FFF8        -8
      65529        -7  1111111111111001      -111      FFF9        -7
      65530        -6  1111111111111010      -110      FFFA        -6
      65531        -5  1111111111111011      -101      FFFB        -5
      65532        -4  1111111111111100      -100      FFFC        -4
      65533        -3  1111111111111101       -11      FFFD        -3
      65534        -2  1111111111111110       -10      FFFE        -2
      65535        -1  1111111111111111        -1      FFFF        -1
          0         0                 0         0         0         0
          1         1                 1         1         1         1
          2         2                10        10         2         2
          3         3                11        11         3         3
          4         4               100       100         4         4
          5         5               101       101         5         5
          6         6               110       110         6         6
          7         7               111       111         7         7
          8         8              1000      1000         8         8
          9         9              1001      1001         9         9
         10        10              1010      1010         A         A

 \ exercise 3.10, true and false data sets
 : true_set  ( -- )
         cr
         4 4 = u.b cr
         4 5 <> u.b cr
         4 5 < u.b cr
         4 3 > u.b cr
         0 0= u.b cr
         4 0<> u.b cr
         -4 0< u.b cr
         4 0> u.b cr
         true true and u.b cr
         true false or u.b cr
  false not u.b cr ;

 : false_set  ( -- )
         cr
         4 5 = u.b cr
         4 4 <> u.b cr
         4 3 < u.b cr
         4 5 > u.b cr
         2 0= u.b cr
         0 0<> u.b cr
         4 0< u.b cr
         -4 0> u.b cr
         false true and u.b cr
         false false or u.b cr
         true not u.b cr ;

 \ Compute area of a circle to three decimal places (character printing)
 : CIRCLE_AREA ( r -- )
         DUP * 355 113 */MOD
         ." Area = " 5 .r
         ASCII . EMIT
         5 0  DO
              10 * 113 /MOD 48 + emit
              LOOP DROP ;
 : TEST_CIRC ( -- )
        11 1 DO CR I CIRCLE_AREA LOOP ;
 \ > an even better solution than  1 .R  is   48  +  EMIT
 \ > Can you explain why this will work??
 \ This turns the numerical digit into an ASCII character. That's a
 \ pretty good solution. Below is output for modified CIRCLE_AREA
 test_circ
 Area =     3.14159
 Area =    12.56637
 Area =    28.27433
 Area =    50.26548
 Area =    78.53982
 Area =   113.09734
 Area =   153.93805
 Area =   201.06194
 Area =   254.46902
 Area =   314.15929
-----
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