5 SCREEN 12
10 PRINT "Derivative is "; CHR$(127); "y/"; CHR$(127); "x as "; CHR$(127); "x->0"
15 PRINT "Derivative for "; CHR$(251); "(1+(x^2))=x/"; CHR$(251); "(1+(x^2))"
30 PRINT "Program calculates the slope y1-y2/x1-x2"
31 PRINT "which for small changes of x and y"
32 PRINT "should be close to the derivative"
40 DEFDBL A-Z
50 a = 2
60 b = 1.99999#
70 c = .00001#
80 x = a
90 GOSUB 300
100 e = y
120 x = b
130 GOSUB 300
140 f = y
141 j = a + c
142 x = j
143 GOSUB 300
144 k = y
150 g = (e - f) / c
151 l = (k - e) / c
152 m = (g + l) / 2
160 PRINT "Slope at x=2 "; CHR$(127); "x=.00001 is"; m
161 i = 2 / ((5) ^ (1 / 2))
162 PRINT "The derivative at x=2 is "; i
170 SYSTEM
300 y = (1 + (x ^ 2)) ^ (1 / 2)
310 RETURN