Introduction to BASIC   Curves and Graphs

Coordinate System
Before drawing curves or graphs, the coordinate system should be set.

SET WINDOW x₁, x₂, y₁, y₂
sets the coordinate system where the range of x coordinate is from x₁ to x₂, and the range of y coordinate is from y₁ to y₂.

Coordinate axes
DRAW axes
draws the axes of coordinate.

PLOT LINES
PLOT LINES statements draw segments continuously.
A sequential execution of
PLOT LINES: x,y;
draws an approximation of a curve.
Example.

10 DEF f(x)=x^3-x
20 SET WINDOW -4,4,-4,4
30 DRAW axes
40 FOR x=-4 TO 4 STEP 0.01
50     PLOT LINES: x,f(x);
60 NEXT x
70 END

Refer to PLOT LINES