J Version 4        Keyboard Actions                                  Help 1 of 5                                                                                ^ indicates CTRL.  ^D terminates the session.                                                                                                                   PAGE-UP and PAGE-DOWN scroll lines.                                             ^PAGE-UP and ^PAGE-DOWN scroll pages.                                           ^HOME and ^END scroll to beginning and end.                                     ^LEFT and ^RIGHT scroll left and right, and switch to wide mode. ESC resets.                                                                                    UP and DOWN cursor keys move the bar (line marker).                             ^ENTER inserts the bar line in the input area.                                  ^BACKSPACE deletes input from cursor to end.                                                                                                                    ESC resets and discards input line(s). ESC allows more output when STOPPED.     SCROLL-LOCK stops output after 50 lines without input. ESC allows another 50.   ^C and ^BREAK interrupt execution.                                              ^F1 changes the number of displayed rows (VGA only).                            PRINT-SCREEN prints the screen. The DOS utility BIGPRTSC enables printing           more than 25 screen rows.                                                                                                                                   F1 invokes the help screens (this screen).                                      Within the help screens, F1, PAGE-UP, and PAGE-DOWN scroll pages.                                                                                               The expression 8!:1(1) eliminates the "flashing" effect on CGA displays.                                                                                        J Version 4        Editor                                            Help 2 of 5                                                                                8!:9 y edits y, a string with lines delimited by linefeeds (10{a.).             Within the editor:                                                                                                                                              ^ indicates CTRL.                                                                                                                                               ^F1    changes the number of displayed rows (VGA only).                         ^F2    switches between editor and standard screen.                             ^ENTER in standard screen copies bar line to block at end of edit text.         ^F3    undoes last deletion (BS, DEL, ^BS, and DEL in block).                   ^F5    blocks a line.                                                           ^F6    starts, marks, or releases a block.                                      ^F7    copies block to the cursor.                                              ^F8    moves block to the cursor.                                               ^F10   exits editor.                                                            ^BREAK exits edit mode, leaving the original text unmodified.                                                                                                   BLOCK  The status line indicates BLOCK when a block is marked or started,              and in that state, some actions are ignored.                             FULL   The status line indicates FULL if the edit buffer is too small                  for a request.                                                                                                                                                                                                                                                                                                           J Version 4        Language Summary I                                Help 3 of 5                                                                                =  Self-Classify . Equal    Is (Local)               Is (Global)                <  Box . Less Than          Floor . Lesser of        Decrement . Less Or Equal  >  Open . Larger Than       Ceiling . Larger of      Increment . Larger Or Equal_  Negative Sign / Infinity Indeterminate            Infinity                                                                                                   +  Conjugate . Plus         Real/Imag . GCD (Or)     Double . Not-Or            *  Signum . Times           Polar . LCM (And)        Halve . Not-And            -  Negate . Minus           Not (1-) . Less          Square . Match             %  Reciprocal . Divide      Matrix Inv . Mat Divide  Square Root . Root                                                                                         ^  Exponential . Power      Natural Log . Log        Power . Chain              $  Shape Of . Shape         Suite                    Self-Reference             ~  Both . Cross             Nub .                    Nub Sieve . Not-Equal      |  Magnitude . Residue      Reverse . Rotate         Transpose                                                                                                  .  Det . Dot Product        Even                     Odd                        :  Explicit Definition      Obverse                                             ,  Ravel . Append           Ravel Items . Apnd Items Itemize . Laminate         ;  Raze . Link              Cut                      Word Formation .                                                                                           #  Tally . Copy             Base 2 . Base            Antibase 2 . Antibase      !  Factorial . Out Of       Fit (Customize)          Foreign                                                                                                    J Version 4        Language Summary II                               Help 4 of 5                                                                                /  Insert . Table           Oblique . Key            Grade Up . Sort            \  Prefix . Infix           Suffix . Outfix          Grade Down . Sort          [  Same . Left              Lev                                                 ]  Same . Right             Dex                                                                                                                                 {  Catalog . From           Head . Take              Tail .                     }  Amend                    Behead . Drop            Curtail .                  "  Rank                     Do . Do Left If Error    Format                     `  Gerund                                            Evoke Gerund                                                                                               @  Atop                     Agenda                   At                         &  With / Compose           Under (Dual)             Appose                     ?  Roll . Deal                                                                                                                                                  )  Label                    a. Alphabet              A. Atomic Permute          b. Boolean                  c. Characteristic        C. Cycle-Direct . Permute  e. Raze In . Member (In)    E. . Member of Interval  f. Fix                                                                                                     i. Integers . Index Of      j. Imaginery . Complex   NB. Comment                o. Pi Times . Circle        p. Polynomial            r. Angle . Complex         x. Left Argument            y. Right Argument        0: Zero                                                                         1: One                                                                                                     J Version 4        !: Enumeration                                    Help 5 of 5                                                                                0!:0  Host                 4!:0  Name Class           9!:0   Qry Random Link    0!:1  Host (No Result)     4!:1  Name List            9!:1   Set Random Link    0!:2  Script               4!:55 Erase                9!:4   Qry Prompt         0!:3  Silent Script        5!:0  Fix                  9!:5   Set Prompt         0!:55 Terminate Session    5!:1  Atomic  Rep          9!:6   Qry Box Chars      1!:1  File Read            5!:2  Display Rep          9!:7   Set Box Chars      1!:2  File Write           5!:3  String  Rep          9!:8   Qry Error Msgs     1!:3  File Append          5!:4  Tree    Rep          9!:9   Set Error Msgs     1!:4  File Size            6!:0  Time Now             10!:k  (LinkJ) C Function 1!:11 File Indexed Read    6!:1  Time Since Start     128!:0 QR Decomposition   1!:12 File Indexed Write   6!:2  Time to Execute      128!:1 R Inverse          1!:55 File Erase           6!:3  Delay                                          2!:0  WS Name Class        7!:0  Space Now                                      2!:1  WS Name List         7!:1  Space Since Start                              2!:2  WS Save              7!:2  Space to Execute                               2!:3  WS PSave             8!:0  Qry CGA Mode                                   2!:4  WS Copy              8!:1  Set CGA Mode                                   2!:5  WS PCopy             8!:4  Qry Screen Attr                                2!:55 WS Erase Object      8!:5  Set Screen Attr                                3!:0  Internal Type        8!:7  Refresh Screen                                 3!:1  To   Internal Rep    8!:9  Edit                                           3!:2  From Internal Rep                                                                                                                                         