E A

C FOCAL15 V9A
03.10 T !"WE CAN MIX ANSWERS AND WRITING ON THE SAME LINE OF TYPING.
03.11 T !"FOR EXAMPLE:";W 3.13
03.12 G 3.14
03.13 T !"MY ANSWER IS Z=",Z
03.14 T !"YOU MUST HAVE CALCULATED Z PREVIOUSLY. STOP AND TRY THIS";Q
03.20 T !"A VERY USEFUL COMMAND IS ASK (OR A). THIS CAUSES THE
03.21 T !"PROGRAM TO STOP AND WAIT WHILE YOU TYPE IN A NUMBER.
03.22 T !"FOR EXAMPLE: A X    ALLOWS YOU TO TYPE IN A VALUE FOR X.
03.23 T !"YOU CAN USE QUOTES TO WRITE BEFORE IT ASKS"!;W 3.25
03.24 G 3.26
03.25 A !"X= ",X," Y=",Y
03.26 T !"CHANGE YOUR PREVIOUS PROGRAM TO TRY THIS";Q
03.30 T !"THE DO (OR D) INSTRUCTION IS FAIRLY EASY TO UNDERSTAND
03.31 T !"BUT IT IS DIFFERENT FROM FORTRAN OR PL1 IN CASE YOU ARE
03.32 T !"USED TO PROGRAMMING IN THOSE LANGUAGES.  DO  SHIFTS
03.33 T !" CONTROL TO A STATEMENT OR TO A GROUP AND THE PROGRAM
03.34 T !" COMES BACK TO THE STARTING POINT WHEN IT FINDS THE
03.35 T !"COMMAND RETURN (OR R).  USE WRITE 13 TO SEE A
03.36 T !"SUB-ROUTINE IN A GROUP BY ITSELF. TRY D 13 IN ONE
03.37 T !"OF YOUR PREVIOUS PROGRAMS.";Q
03.38 T !"WRITE A PROGRAM IN GROUP 8 AND USE D 8 TO EXECUTE THE
03.39 T !"ENTIRE GROUP.  PUT THE D 8 COMMAND IN ANOTHER GROUP,
03.40 T !"AND NOTE HOW CONTROL SHIFTS AROUND.";Q
03.50 T !"LET'S SEE IF YOU CAN HANDLE ONE OF THE MORE DIFFICULT
03.51 T !"COMMANDS, IF (OR I). THIS IS A DECISION COMMAND WHICH
03.52 T !"ALLOWS BRANCHING IN THE PROGRAM. FOR EXAMPLE,"!;
03.53 T !"  I (X-1) 3.55,3.51,3.52";Q
03.54 T !"THIS IS TRANSLATED:"!"  IF X-1 IS NEGATIVE, GO TO 3.55
03.55 T !"  IF X-1 = 0, GO TO 3.51"!"  IF X-1 IS +,GO TO 3.52
03.56 A !"(HIT RETURN KEY)",AN
03.57 T !"PERHAPS YOU CAN UNDERSTAND THIS BETTER FROM AN EXAMPLE.";W 14
03.66 T !"THIS PROGRAM AVERAGES GRADES.  EACH TIME A GRADE IS ENTERED
03.67 T !"IT INCREMENTS G. THE IF COMMAND KEEPS IT ASKING FOR GRADES
03.68 T !"UNTIL G=N, THE NUMBER OF STUDENTS.  WHEN G=N, IT TYPES OUT
03.69 T !"THE ANSWERS.  TRY MY LITTLE GRADE AVERAGE PROGRAM BY D 14";Q
03.79 T !"TO USE THE FOR (OR F) INSTRUCTION INTELLIGENTLY, YOU NEED
03.80 T !"TO KNOW A LOT MORE ABOUT WRITING PROGRAMS.  LET'S JUST
03.81 T !"SEE AN EXAMPLE HERE AND NOT WORRY ABOUT THE DETAILS.
03.82 T !"YOU USUALLY USE SUBSCRIPTED VARIABLES OR AN INDEX OR BOTH.
03.83 T !"A TYPICAL COMMAND IS:"!;S N=2;W 3.85
03.84 G 3.86
03.85 F I=1,N;D 13;Q
03.86 T !"THIS TRANSLATES: FOR VALUES OF N STARTING AT 1 AND GOING
03.87 T !"UP IN STEPS OF 1, EXECUTE GROUP 13.  WITHIN GROUP 13
03.88 T !"YOU WOULD USE I AS A SUBSCRIPT OR AN INDEX AND WOULD THUS
03.89 T !"BE DOING THE CALCULATION OVER SEVERAL TIMES WITH THESE
03.90 T !"CHANGING VALUES OF I. TRY  GO 3.85  IF YOU WISH AND COME BACK
03.91 T !"TO 4.01 FOR CLOSING REMARKS";Q
04.01 L I TEACH4
04.02 Q
07.99 Q
13.10 A !"GIVE ME A NUMBER.",NU
13.20 S NSQ=NU * NU
13.30 T !"THE SQUARE OF YOUR NUMBER =  ",NSQ
13.98 RETURN
14.60 A !"GRADE AVERAGES"!"NUMBER OF STUDENTS = ",N
14.61 S G=0.0;S SUM=0.0
14.62 I (G-N) 14.63,14.64,14.64
14.63 S G=G+1;A !"GRADE = ",V;S SUM=SUM+V;G 14.62
14.64 S AVE=SUM/N;T !"AVERAGE = ",AVE
14.99 T !!;G 5.98

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