genius-common 1.0.21-1 / usr / share / genius / examples / newton-calc-sqrt2.gel

# Category: Calculus
# Name: Newton's method for sqrt(2)
#
# Calculate some number of iterations of Newton's method for sqrt(2)

# Try different functions here to try to get roots of.  Note that
# if genius can't take derivative you can set the derivative function
# df below.
function f(x)=x^2-2;

#initial guess
c1 = 2;

#iterations to run
iters = 9;

# how long to pause after each iteration
thepause = 1;

df = SymbolicDerivative(f);

old_MaxDigits = MaxDigits;
old_FloatPrecision = FloatPrecision;

MaxDigits = 0;
FloatPrecision = 192;

c = c1;
for n = 1 to iters do (
  print("c("+n+") = ");
  print(float(c));
  nc = c-float(f(c)/df(c));
  wait(thepause);
  c = nc;
);

MaxDigits = old_MaxDigits;
FloatPrecision = old_FloatPrecision;