puppybasic intro ch. 04 - numbers are key

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numbers are key                                                          
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                  an intro to puppybasic                                 
                                                                         
                  chapter 4: numbers are key                             
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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numbers are key                                                          
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noooo! not math!                                                         
                                                                         
seriously, everything a computer does is enumerating and counting;       
math can't be avoided, but most of the time it will not be painful.      
in programming, colors are numbers, sounds are numbers, letters are      
numbers, and numbers are the difference between a program that does      
something and a program that doesn't; so here are some ways to work      
with them...                                                             
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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numbers are key                                                          
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first of all, operations: use of x+y adds the two, use of x-y            
subtracts y from x, x*y gives the product, and a forward slash, "/"      
will divide. exponents use the notation x^y, where x is raised to        
the power of y.                                                          
                                                                         
math works well with variables:                                          
                                                                         
x = 7                                                                    
y = x * 5            ___________________________________________________ 
PRINT "7 times 5 ="; _7 times 5 = 35____________________________________ 
PRINT y              ___________________________________________________ 
                                                                         
                                                                         
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you can use parentheses in puppybasic the same way you use them in           
equations on paper, (except of course that you will want to enter        
them with a keyboard, not a pencil.)                                     
                                                                         
moving on, ABS(x) automatically converts any value below zero to the     
same value over zero, if you like. yes that's right, it just removes     
the little line from a negative number.                                  
                                                                         
q = ABS((5 / 7) * -1) __________________________________________________ 
PRINT q               __.7142857________________________________________ 
                      __________________________________________________ 
                                                                         
                                                                         
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INT                                                                      
                                                                         
is similar in its simplicity to ABS but more likely to prove useful,     
INT(x) does nothing to integers at all. if x is not an integer however,  
INT will force it to become one, eliminating the fraction (or decimal).  
chances are, if you stay with puppybasic you will be using this 
function, so go ahead and make yourselves aquainted.                                  
                                                                         
PRINT INT(7 / 3); INT(-4.9); INT(4.9) __________________________________ 
                                      __2_-5__4_________________________ 
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MOD                                                                      
                                                                         
is a weird function with a weird name. (it stands for "modulus.") it     
forces a long set of numbers into a smaller set: say you have a number   
like... 42 (and why wouldn't you?) but you want a number in the range    
between 0 and 15, because the number is *supposed to* represent a        
color. you could of course reject any number over 15 and set it as 15,   
or you could instead say 42 MOD 16 (much, much more useful with          
variables, and even loops or counters) which will invariably (heh)       
give you a number in the range 0 to 15. let's illustrate with smaller    
numbers and see if it makes sense:                                       
                                                                         
                                                                         
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numbers are key                                                          
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              ____________                                               
PRINT 0 MOD 7 __0_________                                               
PRINT 1 MOD 7 __1_________                                               
PRINT 2 MOD 7 __2_________                                               
PRINT 3 MOD 7 __3_________                                               
PRINT 4 MOD 7 __4_________                                               
PRINT 5 MOD 7 __5_________                                               
PRINT 6 MOD 7 __6_________                                               
PRINT 7 MOD 7 __0_________ again!                                        
PRINT 8 MOD 7 __1_________                                               
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the most fun you can have with modulus is in graphics routines, while    
its best purpose may be handling (really) long division. if you never    
use it, well, that's one less thing.                                     
                                                                         
i'll follow this odd numeric function with one that could be the hardest 
to avoid using...                                                        
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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VAL                                                                      
                                                                         
n = VAL(q$) turns the string q$ into the value n, so the string          
" 0.557" becomes a simple .557, to the program: something which can      
be added to, subtracted from, and otherwise used as a number, which      
strings (otherwise) cannot. this is priceless when working with data     
from files and the keyboard.                                             
                                                                         
q$ = "27a"                                  ____________________________ 
PRINT VAL("hi there"); VAL(q$); VAL("4.91") __0__27__4.91_______________ 
                                            ____________________________ 
                                                                         
                                                                         
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if you need a sufficiently "random" number, for dice, a "magic"          
8-ball, or just a cool display on the screen, using the RND function     
with INT and the number of "sides" you want:                             
                                                                         
n = INT(RND * 6)                                                         
                                                                         
will return a number 0 to 5, and you can have each number represent      
the side of a die or anything you like.                                  
                                                                         
                                                                         
                                                                         
                                                                         
                                                                         
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prefer 1 to 6? why not?                                                  
                                                                         
n = INT(RND * 6 + 1)                                                     
                                                                         
will return numbers more specifically useful to dice. (you may be        
thinking, "why not 'RND * 7'?", and the simple answer is "'cause it's    
wrong!"                                                                  
                                                                         
the useful answer is that RND * 6 + 1 produces a number of 6 possible    
numbers, with 1 added to that number, but RND * 7 actually creates a     
7-sided die, something i've never seen in my life.)                      
                                                                         
                                                                         
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you will find that even if rolled 100 times, the 100 results you get     
will be the same 100 results every time you use the program. to get      
around this, the code RANDOMIZE TIMER will "seed" the RND function.      
then all you have to do to roll the same dice twice is start at          
precisely the same time of day as last time, to the millisecond,         
accounting also for the fact that the clock circuit in your computer     
is probably not as accurate a timepiece as your digital wristwatch,      
even if you can set it from the atom clock: and good luck to you.        
                                                                         
RANDOMIZE TIMER                                                          
? "this number will be random enough:"; INT(RND * 10)                    
                                                                         
                                                                         
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q = SGN(n)                                                               
                                                                         
will set q to -1 if n is less than 0, set q to 0 if n is 0, and set      
q to 1 if n is more than 0. i've used this, but not that often.          
                                                                         
SQR(n)                                                                   
                                                                         
is the square root of n, and is almost always easier to use than a       
pencil and paper.                                                        
                                                                         
                                                                         
                                                                         
                                                                         
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i use these to do neat things with graphics, maybe you can find some     
other use for trig. here are some of the trig functions:                 
                                                                         
cosine: COS(n)                                                           
sine: SIN(n)                                                             
tangent: i'm just thrilled with the program i made using this, it...     
                                                                         
sorry, i meant to say TAN(n)                                             
n is the angle in radians. radians are equal to degrees * pi / 180.      
                                                                         
                         -= end of chapter 4 =-                          
                                                                         
                                                                         
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an intro to puppybasic                                       (chapter 4) 
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