╘HIS SECTION IS NOT ABOUT THE LIMITS OF OUTER SPACE. ╔T IS ABOUT FINDING THE SMALLEST AND A LARGEST NUMBER IN A LIST OF GIVEN NUMBERS AND ABOUT COPYING NUMBERS WELL INSIDE THE TINY CHIPS IN THE COMPUTER. ╔T ALSO SHOWS HOW TO APPROACH A PROBLEM WITH PENCIL AND PAPER, BEFORE TALKING TO THE COMPUTER.
┴ TYPICAL APPLICATION IS WHEN ONE NEEDS TO KNOW WHO GOT THE HIGHEST SCORE ON A MATH TEST, THE LOWEST SALARY IN YOUR DEPARTMENT AT WORK, OR THE CHEAPEST GOATS FOR SALE. ═ANUALLY CHECKING A LONG LIST CAN BE DONE OF COURSE, BUT A COMPUTER CAN DO IT IN A HURRY. ╘HIS ROUTINE DOES JUST THAT.
// PRG: FIND MIN/MAX //
Ç*FP6
*** ╓┴╥╔┴┬╠┼╙ ***
╬ NUMBER OF ITEMS TO SCAN
╓() LIST OF ITEMS
═╪ HIGHEST NUMBER
═╬ LOWEST NUMBER
*** ╔╬╙╘╥╒├╘╔╧╬╙ ***
╥╒╬ IT. ╘HE PROGRAM STOPS BY ITSELF AT THE END OF SCANNING ╬=20 NUMBERS.
*** ─┼╘┴╔╠╙ ***
╫E HAVE TO IMAGINE, THAT WE HAVE A LONG LIST OF NUMBERS. ┬UT INSTEAD OF TYPING IN SUCH A LIST, WE WILL USE THE COMPUTER'S RANDOM NUMBER GENERATOR TO MAKE US A LIST OF NUMBERS BETWEEN 100 AND 200 AND TO IMMEDIATELY REPORT THE MINIMUM AND THE MAXIMUM VALUES, AS SHOWN IN THIS EXERPT:
// PIC: FINDMN/MX //
╫E CREATEÇúAN ARRAY OR A TABLE OF ╬=20 VALUES ╓, THAT'S THE ─╔═ IN LINE 110 (─╔═ STANDS FOR DIMENSION - IT'S OUR WAY OF TELLING THE COMPUTER TO PREPARE 20 BINS TO HOLD THE NUMBERS). ┘OU MAY CHANGE 20 TO SOME OTHER VALUE. ╔N LINE 120 THE COMPUTER GENERATES THE LIST AND IMMEDIATELY GOES INTO THINKING ABOUT THE SMALL AND THE BIG. ╫E GIVE IT ONLY ONE CHANCE TO LOOK AT ANY ONE NUMBER. ╘HE COMPUTER HAS TO REMEMBER WHAT IT HAS SEEN BEFORE. ┴S CAN BE SEEN FROM THE ILLUSTRATION, IT DOES THE JOB WELL.
*** ╨┼╬├╔╠ ┴╬─ ╨┴╨┼╥ ╙╧╠╒╘╔╧╬ ***
╘O START THE PROCESS, WE TELL A TINY LIE: THAT THE SMALLEST VALUE WE'RE THINKING IS NOW 1,000,000,000. ╘HAT'S THE FUNNY LOOKING 1┼9. ╙IMILARLY, WE SET THE LARGEST VALUE TO A NEGATIVE OF THAT. ╫HY? ╘HE POINT IS TO SWAP, AND REMEMBER WHAT WE LOOKED AT LAST.
╠ET'S PENCIL-PRACTICE IT ON SOME NUMBERS WE CAN HANDLE. ╧UR LIST OF NUMBERS CAN BE 5, 2, 9, 1. ╘HE ANSWER BETTER BE 9 FOR THE MAXIMUM, OR WE'RE IN TROUBLE.
BIG = -1,000,000,000
NUMBER 5 COMES UP
IS 5 BIGER THAN THE CURRENT
TINY BIG OF -1,000,000,000?
YUP, SO WE SET BIG TO BE 5
NUMBER 2 COMES UP
IS 2 BIGGER THAN 5?
NOPE, BIG REMAINS 5
NUMBER 9 COMES UP
IS 9 BIGGER THAN 5?
YUP, SO WE SET BIG TO BE 9
NUMBER 1 COMES UP
IS 1 BIGGER THAN 9?
NOPE, BIG REMAINS 9
╙INCE WE HAVE REACHED THE END OF THE LIST, 9 IS THE ANSWER. ╬OT BAD.
╘HE SAME METHOD, ONLY BACKWARDS, IS USED FOR FINDING THE SMALLEST VALUE. ┴ND THAT'S WHAT LINES 130-140 DO, EXCEPT THAT THEY USE ELEMENTS, OR INDIVIDUAL MEMBERS OF A LIST OF NUMBERS WE CALLED ╓. ╔N THIS WAY, WITH ONE CLEAN SWEEP, WE GET THE WHOLE JOB DONE.
*** ╨╥╧╩┼├╘╙ ***
╘HERE ARE MANY WAYS TO SKIN A CAT. ╘RY SETTING THE FIRST, PHONEY, MIN OR MAX VALUE TO SOMETHING ELSE. ├OULD YOU USE THE FIRTST VALUE OF THE ARRAY? ╫HY OR WHY NOT?
╘RY SETTING ═╬ TO 201 AND ═╪ TO 199. ─O YOU THINK YOU COULD CODE ═╬ AND ═╪ INTO THE RANDOM NUMBER FORMULA? ╥EAD ABOUT ╥╬─ IN THE MANUAL, IT IS A HANDY THING.
╔NSTEAD OF USING AN ARRAY, PUT SOME VALUES IN ─┴╘┴ LINES. ╥EAD THEM IN AND PERFORM AN ANALOGOUS PROJECT.
*** ═┼┴╬╔╬╟ ╧╞ ╓┴╥╔┴┬╠┼╙ ***
╔F YOU'RE CURIOUS ABOUT HOW COMPUTERS WORK, YOU MAY WELL ASK YOURSELF WHAT HAPPENS WHEN WE SAY ═╬=╓(╩). ╬OTHING MUCH REALLY: ╫HAT IS ON THE RIGHT OF THE EQUALS SIGN IS COPIED TO THE VARIABLE ON THE LEFT OF THE EQUALS SIGN. ╓(╩) REPLACES THE CURRENT VALUE OF ═╬ (WHATEVER THAT WAS). ╓(╩) REMAINS INTACT. ╘HAT IS ANOTHER VALUE AS FAR AS THE COMPUTER IS CONCERNED, BUT ITS COPY HAS BEEN PLACED IN ═╬.
