tests: add examples/montecarlo.nit

[nit.git] / examples / montecarlo.nit

diff --git a/examples/montecarlo.nit b/examples/montecarlo.nit
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+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Approximation of Pi using a Monte Carlo simulation.
+#
+# This is just an example of basic math and random operations.
+module montecarlo
+
+# Number of iterations
+var n = 1000
+if args.not_empty then n = 2 ** args.first.to_i
+
+# Threshold for output
+var j = 1
+
+# Number of hits
+var h = 0
+
+for i in [1..n] do
+       # Random position in the ([0..1[,[0..1[) square
+       var x = 1.0.rand
+       var y = 1.0.rand
+
+       # Hit if in the circle
+       if x*x + y*y <= 1.0 then h += 1
+
+       # Print
+       if i >= j or i == n then
+               print "i={i} h={h} p={(4.0*h.to_f/i.to_f).to_precision(6)}"
+               j *= 2
+       end
+end