ln and e^x on the 16C?

[Bob Patton]

Hi Dave,

Here's a crude algo I developed for 4 -bangers with memory. It might be a start.
Natural log ln(v)
0.6 to 1.65, 6 digits, 39 keystrokes

y = -(v - 1)/(v + 1) = -((v + 1) - 2)/(v + 1)
ln(v) = ((((5y^2/7) - 1)^(-1) X 42 - 8)y^2 / 75 - 2)y
for v < 0.6 multiply by e n times until in range; subtract n at end
for v > 1.65 divide by e n times until in range; add n at end

Exponential e^v
-1 to +1, 7 digits, 36 keystrokes

e^v = ((((v^2 + 42)/98)^(-1) X v + v - 20)v/40 + 1)^(-1) X v + 1