Open Mind Tree

PROGRAM decision1
LET x = 0
DO while x < 20
   LET x = x + 1
   IF x <= 10 then
      LET f = 1/x
   ELSE
      LET f = 1/(x*x)
   END IF
   PRINT x,f
LOOP
END

PROGRAM decision2
LET x = 0
DO while x <= 30
   IF x = 0 then
      LET f = 0
   ELSEIF x <= 10 then
      LET f = 1/x
   ELSEIF x <= 20 then
      LET f = 1/(x*x)
   ELSE
      LET f = 1/(x*x*x)
   END IF
   PRINT x,f
   LET x = x + 1
LOOP
END

PRINT "x","y","z"
PRINT x,y,z
PRINT                     ! skip line
PRINT "time ="; t
PRINT tab(7);"time";tab(17);"position";tab(28);"velocity"

ASK SET CURSOR max_row,max_col

PROGRAM space_bar
DO
   GET KEY k
   PRINT k
LOOP until k = 32                 ! pressing space bar exits loop
END

PROGRAM mouse
DO
   ! return current x and y window coordinates and state of mouse
   GET MOUSE x,y,s
   IF s = 1 then
      PRINT "button down",x,y
   ELSE IF s = 2 then
      PRINT "button clicked",x,y
   ELSE IF s = 3 then
      PRINT "button released",x,y
   END IF
LOOP
END

PROGRAM single_column
! save data in a single column
! file$ example of string variable
INPUT prompt "name of file for data? ": file$
! channel number #1 associated with file and can be passed to
! subroutines
! various options may be specified in OPEN statement
! access output: write to file only
! create newold: open file if exists, else create new file
OPEN #1: name file$, access output, create newold
! True BASIC does not overwrite data in a text file
! ERASE #1                          ! erase contents of file
! RESET #1: end   ! allows data to be added to end of file
FOR i = 1 to 4
    LET x = i*i
    PRINT #1: x                   ! print column of data
NEXT i
CLOSE #1
! channel # irrelevant if only one channel open at a time
OPEN #2: name file$, access input
FOR i = 1 to 4
    INPUT #2: y                   ! print column of data
    PRINT y
NEXT i
! files automatically closed when program terminates
CLOSE #2                          ! not necessary but good practice
END

PROGRAM example_data
DIM x(6)
DATA 4.48,3.06,0.20,2.08,3.88,3.36
FOR i = 1 to 6
    READ x(i)                ! reads input from DATA statement
NEXT i
END

SET WINDOW xmin, xmax, ymin, ymax

PLOT POINTS: x,y;

PLOT LINES: x1,y1; x2,y2;

PROGRAM plot_f                     ! plot analytical solution
CALL initial(t,tmax,r,Ts,T0)
CALL set_up_window(t,tmax,Ts,T0)
CALL show_plot(t,tmax,r,Ts,T0)
END

SUB initial(t,tmax,r,Ts,T0)
    LET t = 0
    LET T0 = 83                   ! initial coffee temperature (C)
    LET Ts = 22                   ! room temperature (C)
    INPUT prompt "cooling constant r = ": r
    INPUT prompt "duration = ": tmax   ! time (minutes)
    CLEAR
END SUB

SUB set_up_window(xmin,xmax,ymin,ymax)
    LET mx = 0.01*(xmax - xmin)   ! margin
    LET my = 0.01*(ymax - ymin)
    SET WINDOW xmin - mx,xmax + mx,ymin - my,ymax + my
    ! default background color black on all computers except Macintosh
    PLOT xmin,ymin; xmax,ymin     ! abbreviation for PLOT LINES:
    PLOT xmin,ymin; xmin,ymax
END SUB

SUB show_plot(t,tmax,r,Ts,T0)
    DECLARE DEF f                 ! declare use of external function
    SET COLOR "red"
    DO while t <= tmax
       PLOT t,f(t,r,Ts,T0);       ! abbreviation for PLOT LINES
       LET t = t + 0.1
    LOOP
END SUB

DEF f(t,r,Ts,T0)
    LET f = Ts - (Ts - T0)*exp(-r*t)
END DEF

PROGRAM no_circle
LET r = 1                         ! radius of circle
SET WINDOW -r,r,-r,r
SET COLOR "blue"
BOX CIRCLE -r,r,-r,r
! FLOOD 0,0: start from the point 0,0 and color continuous pixels 
! until boundary of region is reached
FLOOD 0,0
END

PROGRAM circle
LET r = 1                         ! radius of circle
CALL compute_aspect_ratio(r,xwin,ywin)
SET WINDOW -xwin,xwin,-ywin,ywin
SET COLOR "blue"
BOX CIRCLE -r,r,-r,r              ! draw circle
END

SUB compute_aspect_ratio(r,x,y)
    LET m = 0.1*r                 ! margin
    LET size = r + m
    ! px, py: # pixels in horizontal and vertical direction
    ASK PIXELS px,py
    IF px > py then
       LET aspect_ratio = px/py
       LET x = aspect_ratio*size
       LET y = size
    ELSE
       LET aspect_ratio = py/px
       LET x = size
       LET y = aspect_ratio*size
    END IF
END SUB

PROGRAM multiple_windows
! note passing of channel numbers
CALL initial(#1,#2)               ! initialize windows
CALL show(#1)
CALL show(#2)
END

SUB initial(#1,#2)
    OPEN #1: screen 0,0.5,0,1     ! left-half of screen
    SET WINDOW 0,1,0,1
    SET COLOR "green"
    OPEN #2: screen 0.5,1,0,1     ! right-half of screen
    SET COLOR "red"
    SET WINDOW 0,1,0,1
END SUB

SUB show(#9)
    WINDOW #9                     ! note use of dummy variable
    FOR i = 1 to 100
        PLOT rnd,rnd;
    NEXT i
END SUB

LET file_name$ = "config.dat"

PROGRAM string
LET a$ = " "
LET b$ = "good"
PRINT b$
LET b$ = b$ & a$ & "morning"     ! & for concatenation
PRINT b$
LET c$ = b$[1:4]                  ! extract substring
PRINT c$
END

PROGRAM read_file
! open n successive files
LET n = 20
FOR i = 1 to n
    LET si$ = str$(i)
    LET file_name$ = "config" & si$ & ".dat"
    OPEN #i: name file_name$, access output, create newold
    PRINT #i: file_name$
    PRINT file_name$
    CLOSE #i
NEXT i
END

factorial(n) = n! = n(n-1)(n-2) ... 1

factorial(n) = n factorial(n-1)

PROGRAM n!
DECLARE DEF f
LET n = 11
PRINT "n! ="; f(n)
END PROGRAM

DEF f(n)
    IF n <= 0 then
       LET f = 1
    ELSE
       LET f = n*f(n-1)
    END IF
END DEF

PROGRAM show_public
PUBLIC L,spin(3,3)
CALL initial
FOR y = 1 to L
    FOR x = 1 to L
        PRINT spin(x,y);
    NEXT x
    PRINT
NEXT y
END

SUB initial
    DECLARE PUBLIC L,spin(,)
    LET L = 3
    FOR y = 1 to L
        FOR x = 1 to L
            IF rnd < 0.5 then
               LET spin(x,y) = 1
            ELSE
               LET spin(x,y) = -1
            END IF
        NEXT x
    NEXT y
END SUB

PROGRAM show_public
OPTION TYPO
PUBLIC L,spin(3,3)
LOCAL x,y
CALL initial
FOR y = 1 to L
    FOR x = 1 to L
        PRINT spin(x,y);
    NEXT x
    PRINT
NEXT y
END

SUB initial
    DECLARE PUBLIC L,spin(,)
    LOCAL x,y
    LET L = 3
    FOR y = 1 to L
        FOR x = 1 to L
            IF rnd < 0.5 then
               LET spin(x,y) = 1
            ELSE
               LET spin(x,y) = -1
            END IF
        NEXT x
    NEXT y
END SUB

LET direction = int(4*rnd) + 1
SELECT CASE direction
CASE 1
     LET x = x + 1
CASE 2
     LET x = x - 1
CASE 3
     LET y = y + 1
CASE 4
     LET y = y - 1
CASE else
     PRINT "error"
END SELECT

DIM usave(0:21)
MAT usave = 1.0

PROGRAM example_matrix
! illustrate simple matrix arithmetic
DIM A(4),B(4),C(4),S(2,2),T(2,2),SI(2,2)
MAT A = 1
MAT B = 2*A
MAT C = A + B
MAT PRINT A,B,C
LET dot_product = dot(A,B)        ! dot product of A and B
MAT C = A*B                       ! matrix product
DATA 1,3,4,8
MAT READ S
MAT PRINT C,S
MAT T = Trn(S)                    ! transposed matrix
MAT SI = Inv(S)                   ! inverse matrix
MAT PRINT T,SI
! check that matrix of most recently inverted matrix is not too small
print det
END