8146237: PREFER from Features API taking precedence over catalog file
Reviewed-by: lancea
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// Simple sample demonstrating "fixed point" computation with Streams
// See also https://mitpress.mit.edu/sicp/chapter1/node21.html#secprocgeneralmethods
var Stream = Java.type("java.util.stream.Stream");
// generic fixed point procedure
function fixed_point(f, init_guess) {
var tolerance = 0.00001;
function close_enough(v1, v2) Math.abs(v1 - v2) < tolerance;
var prev;
return Stream.iterate(init_guess, f)
.filter(function(x) {
try {
return prev == undefined? false : close_enough(prev, x);
} finally {
prev = x;
}
})
.findFirst()
.get();
}
// solution to x = cos(x)
print(fixed_point(Math.cos, 1.0))
// solution to x = sin(x) + cos(x)
print(fixed_point(function(x) Math.sin(x) + Math.cos(x), 1.0));
// square root by Newton's method
// http://en.wikipedia.org/wiki/Newton's_method
function sqrt(n)
fixed_point(function(x) (x + n/x) / 2, 2.0);
print(sqrt(2))
print(sqrt(3))