LET e = 2.71828182845904523536
DEF f(x)=x^2
DEF g(x)=x^(1/2)
DEF q(x)=e^x
DEF h(x)=LOG(x)
SET WINDOW -4,4,-2,6
DRAW grid
SET LINE WIDTH 2
PLOT LINES: 0,-2;0,6
PLOT LINES: -4,0;4,0
FOR x=-4 TO 4 STEP 0.01
   PLOT LINES: x,x;
NEXT x
PLOT LINES
SET LINE COLOR 4
FOR x=-4 TO 4 STEP 0.01
   PLOT LINES: x,f(x);
NEXT x
PLOT LINES
FOR x=0 TO 4 STEP 0.01
   PLOT LINES: x,g(x);
NEXT x
PLOT LINES
FOR x=0 TO 4 STEP 0.01
   PLOT LINES: x,-g(x);
NEXT x
PLOT LINES
SET LINE COLOR 2
FOR x=-4 TO 4 STEP 0.01
   PLOT LINES: x,q(x);
NEXT x
PLOT LINES
FOR x=0.01 TO 4 STEP 0.01
   PLOT LINES: x,h(x);
NEXT x
PLOT LINES
END