[Averages/Arithmetic mean - Rosetta Code]

[EDSAC program (Initial Orders 2) to find and print the average of
   a sequence of 35-bit fractional values.
 Values are read from tape, preceded by an integer count.]

[Library subroutine M3, runs at load time and is then overwritten.
 Prints header; here, last character sets teleprinter to figures.]
          PF GK IF AF RD LF UF OF E@ A6F G@ E8F EZ PF
      *!!!!!COUNT!!!!!!AVERAGE@&#..   [PZ]

[Main routine: must be at even address]
          T214K GK
    [0]   PF PF         [average value]
    [2]   PF PF         [reciprocal of data count]
    [4]   PF            [data count]
    [5]   PD            [17-bit constant 1; also serves as '0' for printing]
    [6]   @F            [carriage return]
    [7]   &F            [line feed]
    [8]   !F            [space]
    [9]   MF            [dot (in figures mode)]
   [10]   K4096F        [teleprinter null]
[Entry and outer loop]
   [11]   A11@
          G56F          [call library subroutine R4, sets 0D := data count N]
          SD E64@       [exit if N = 0]
          T4F           [clear acc]
          AF T4@        [load and save N (assumed < 2^16)]
   [18]   A18@ G156F    [print N (clears acc)]
          TD            [clear whole of 0D, including sandwich bit]
          T4D           [same for 4D]
          A4@ S2F       [acc := N - 2]
          G66@          [jump to special action if N = 1]
          A2F           [restore N after test]
          T5F           [store N in 4D high word]
          A5@ T1F       [store 1 in 0D high word]
   [29]   A29@ G120F    [call library subroutine D6, sets 0D := 0D/4D]
          AD T2#@       [load and save 1/N]
          T#@           [clear average]
          S4@           [load -N]
[Inner loop]
   [35]   T4@           [update negative loop counter]
   [36]   A36@ G78F     [read next datum to 0D (clears acc)]
          H2#@          [mult reg := 1/N]
          VD            [acc := datum/N]
          A#@ T#@       [add into average]
          A4@ A5@       [increment negative loop counter]
          G35@          [loop until counter = 0]
   [45]   O8@ O8@       [print 2 spaces]
[Print the average value.
 NB: Library subroutine P1 requires non-negative input and prints only the
 digits after the decimal point. Formatting has to be done by the caller.]
   [47]   A#@           [load average (order also serves as minus sign)]
          G52@          [jump if average < 0]
          TD            [pass average to subroutine P1]
          O65@          [print plus sign (or could be space)]
          E56@          [join common code]
   [52]   TD            [average < 0; clear acc]
          S#@ TD        [pass abs(average) to subroutine P1]
          O47@          [print minus sign]
   [56]   O5@ O9@       [common code: print '0.']
   [58]   A58@ G192F    [call P1 to print abs(average)]
          P8F           [8 decimal places]
          O6@ O7@       [print CR, LF]
          E11@          [loop back always (because acc = 0)]
[Jump to here if data count = 0, means end of data]
   [64]   O10@          [print null to flush teleprinter buffer]
   [65]   ZF            [halt the machine (order also serves as plus sign)]
[Jump to here if data count = 1]
   [66]   TF            [clear acc]
   [67]   A67@ G78F     [read datum to 0D]
          AD T#@        [average := datum]
          E45@          [jump to print the average]

[The following puts the entry address into location 50,
 so that it can be accessed via the X parameter (see end of program).
 This is done in case the data is input from a separate tape.]
          T50K P11@ T11Z

[Library subroutine R4.
 Input of one signed integer, returned in 0D.]
          T56K
GKA3FT21@T4DH6@E11@P5DJFT6FVDL4FA4DTDI4FA4FS5@G7@S5@G20@SDTDT6FEF

[Library subroutine R3.
 Input of one long signed decimal fraction, returned in 0D.]
          T78K
          GKT45KP26@TZA3FTHTDT4DA6HT9@H1HS4HT6FIFAFS4HE7HT7FV4DL8FADT4DA6FA5HG8@
          H2#HN4DLDYFTDT28#ZPFT27ZTFP610D@524DP5DPDIFS4HG37@S4DT4DT7FA1HT9@E18@

[Library subroutine D6 - Division, accurate, fast.
 36 locations, workspace 6D and 8D.
 0D := 0D/4D, where 4D <> 0, -1.]
          T120K
          GKA3FT34@S4DE13@T4DSDTDE2@T4DADLDTDA4DLDE8@RDU4DLDA35@
          T6DE25@U8DN8DA6DT6DH6DS6DN4DA4DYFG21@SDVDTDEFW1526D

[Library subroutine P7: print strictly positive integer in 0D.]
          T156K
          GKA3FT26@H28#@NDYFLDT4DS27@TFH8@S8@T1FV4DAFG31@SFLDUFOFFFSF
          L4FT4DA1FA27@G11@T28#ZPFT27ZP1024FP610D@524D!FO30@SFL8FE22@

[Library subroutine P1: print non-negative fraction in 0D, without '0.']
          T192K
          GKA18@U17@S20@T5@H19@PFT5@VDUFOFFFSFL4FTDA5@A2FG6@EFU3FJFM1F

[==========================================================================
 On the original EDSAC, the following (without the whitespace and comments)
 might have been input on a separate tape.]

          E25K TX GK
          EZ            [define entry point]
          PF            [acc = 0 on entry]

[Counts and data values to be read by library subroutines R3 and R4 respectively.
 Note (1) Sign comes *after* value (2) In the data, leading '0.' is omitted.]
7+ 1-2-3-4-5+2-3-
1+ 987654321+
9+ 01+04+09+16+25+36+49+64+81+
9+ 01-04+09-16+25-36+49-64+81-
[Daily minimum temperature (unit = 10 deg. C), Cambridge, UK, January 2000]
31+ 34+14+49+00+04+48+05+48+23-35-07-75+19+03+
    26+27+17-06-52+22-17+18+15+03-33-11-04-01-44+89+95+
0+