sw/os8/v3d/sources/fortran/dectapes/dectape2/dlog.ra

   1 /
   2 /
   3 /       D L O G
   4 /       - - - -
   5 /
   6 / VERSION 5A 4-27-77  PT
   7 /
   8 /LOGE(X)
   9 /
  10 /X=2^N*F
  11 /
  12 /LOGE(X)
  13  /= N*LOGE(2)+LOGE(F)
  14 /
  15 /
  16         SECT    DLOG
  17         JA      #DALOG
  18         DPCHK
  19 /
  20 /IF X<=0 - IT IS AN ERROR
  21         EXTERN  #ARGER
  22 DALERR, TRAP4   #ARGER
  23 /
  24         TEXT    +DLOG  +
  25 DALXR,  SETX    XRDAL
  26         SETB    BPDAL
  27 BPDAL,  F 0.0
  28 XRDAL,  F 0.0
  29         F 0.0
  30         ORG 10*3+BPDAL
  31         FNOP
  32         JA      DALXR
  33         0
  34 DALRTN, JA      .
  35 N,      F 0.0
  36         F 0.0
  37 F,      F 0.0
  38         F 0.0
  39 DAL1,   F 1.0
  40         F 0.0
  41 /
  42 DT7,    7776            /1/7
  43         2222
  44         2222
  45         2222
  46         2222
  47         2221
  48 DT6,    7776            /-1/6
  49         5252
  50         5252
  51         5252
  52         5252
  53         5252
  54 DT5,    7776            /1/5
  55         3146
  56         3146
  57         3146
  58         3146
  59         3146
  60 DT4,    7776            /-1/4
  61         4000
  62         0
  63         0
  64         0
  65         0
  66 DT3,    7777            /1/3
  67         2525
  68         2525
  69         2525
  70         2525
  71         2524
  72 DT2,    7777            /-1/2
  73         4000
  74         0
  75         0
  76         0
  77         0
  78 /
  79 A0,     F 1.84375
  80         F 0.0
  81 A1,     F 1.65625
  82         F 0.0
  83 A2,     F 1.500
  84         F 0.0
  85 A3,     F 1.375
  86         F 0.0
  87 A4,     F 1.250
  88         F 0.0
  89 A5,     F 1.1875
  90         F 0.0
  91 A6,     F 1.09375
  92         F 0.0
  93 A7,     F 1.03125
  94         F 0.0
  95 LA0,    0               /.6118015411059928976
  96         2344
  97         7603
  98         2325
  99         4250
 100         3144
 101 LA1,    0               /.5045560107523952859
 102         2011
 103         2512
 104         4551
 105         3503
 106         7657
 107 LA2,    7777            /.4054651081081643810
 108         3174
 109         6217
 110         5457
 111         7141
 112         1370
 113 LA3,    7777            /.3184537311185346147
 114         2430
 115         3057
 116         0207
 117         0573
 118         0232
 119 LA4,    7776            /.2231435513142097553
 120         3443
 121         7737
 122         0746
 123         5150
 124         4146
 125 LA5,    7776            /.1718502569266592214
 126         2577
 127         6301
 128         6051
 129         7117
 130         2356
 131 LA6,    7775            /.08961215868968712374
 132         2674
 133         1512
 134         1271
 135         2655
 136         1272
 137 LA7,    7773            /.030771658666753687
 138         3740
 139         5154
 140         1636
 141         0313
 142         7764
 143 D16,    F 16.0
 144         F 0.0
 145 D8,     F 8.0
 146         F 0.0
 147 CUM,    F 0.0
 148         F 0.0
 149 DLOGE2, 0
 150         2613
 151         4413
 152         7676
 153         4347
 154         5715
 155 /
 156 /PICK UP X
 157         BASE    0
 158 #DALOG, STARTD
 159         FLDA    10*3
 160         FSTA    DALRTN
 161         FLDA    0
 162         SETX    XRDAL
 163         SETB    BPDAL
 164         BASE    BPDAL
 165         LDX     1,1
 166         FSTA    BPDAL
 167         FLDA%   BPDAL,1         /ADDRESS
 168         FSTA    BPDAL
 169         STARTE
 170         FLDA%   BPDAL           /AND X
 171         JLE     DALERR          /X <= 0 IS ERROR
 172         FSUB    DAL1            /SUB 1.0
 173         JNE     DALA
 174         FCLA                    /LOG(1)=0
 175         JA      DALRTN
 176 /
 177 DALA,   FADD    DAL1            /ADD BACK
 178         FSTA    XRDAL           /STORE AT X
 179 /EXPONENT STORED IN XR0
 180 /MANTISSA STORED IN XR1-5
 181 /PICK UP EXP + MULTIPLY BY LOGE(2)
 182 /
 183         XTA     0
 184         FMUL    DLOGE2
 185         FSTA    N               /N*LOGE(2)
 186 /XRDAL IS NOW FRACTION IN RANGE .5<=F<1.0
 187 /COMPUTE LOG(F) BY
 188 /LOG(F)=LOG(A(K1)*A(K2)...(F))-(LOG(A(K1))+
 189 /       LOG(A(K2))...)
 190 /FIT F IN A 1/16 RANGE
 191 /I.E. 1/2-9/16,9/16-10/16,ETC.
 192 /MULTIPLY F BY APPROPRIATE A(K) MULTIPLIER
 193 /KEEP RUNNING SUM OF LOG(A(K))
 194 /CONTINUE UNTIL F>1
 195
 196 /
 197         LDX     0,0
 198         FLDA    XRDAL
 199         FSTA    F
 200         FCLA
 201         FSTA    CUM
 202 DALB,   FLDA    F
 203         FMUL    D16     /16 REAL PARTS
 204         FSUB    D8              /NEED JUST 8
 205         ATX     1
 206         FLDA    A0,1            /GET MULTIPLIER
 207         FMULM   F
 208         FLDA    LA0,1           /ADD LOG(A(K)) TO SUM
 209         FADDM   CUM
 210         FLDA    F
 211         FSUB    DAL1
 212         JLT     DALB
 213 /NOW F>1. USE TAYLOR SERIES
 214 /LOG(T)=Z-(Z^2)/2+(Z^3)/3+...  WHERE Z=T-1
 215         FLDA    F
 216         FSUB    DAL1    /F-1.0
 217         FSTA    F
 218         FMUL    DT7
 219         FADD    DT6
 220         FMUL    F
 221         FADD    DT5
 222         FMUL    F
 223         FADD    DT4
 224         FMUL    F
 225         FADD    DT3
 226         FMUL    F
 227         FADD    DT2
 228         FMUL    F
 229         FADD    DAL1
 230         FMUL    F
 231         FSUB    CUM
 232         FADD    N
 233         JA      DALRTN
 234 \f