add an example for scipy

Signed-off-by: Jade Abraham <[email protected]>

Author: jabraham17

test/library/packages/Python/examples/scipy/CLEANFILES

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+../../CLEANFILES

test/library/packages/Python/examples/scipy/COMPOPTS

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+../../COMPOPTS

test/library/packages/Python/examples/scipy/EXECENV

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+../../EXECENV

test/library/packages/Python/examples/scipy/integrateQuad.chpl

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+use Python;
+
+var interp = new Interpreter();
+
+var sp = interp.importModule("scipy");
+var spi = interp.importModule("scipy.integrate");
+
+// integrate a Python Function using scipy.integrate.quad
+proc integrate(f: owned Function, a: real, b: real): real {
+  return spi.call("quad", f, a, b).call(real, "__getitem__", 0);
+}
+
+{
+  writeln("Integrating x**3, defined in Python");
+  var f = interp.compileLambda("lambda x,: x**3");
+  writeln(integrate(f, 0.0, 2.0));
+  writeln(integrate(f, 0.0, 4.0));
+  writeln(integrate(f, 0.0, 8.0));
+}
+
+
+// integrate a Chapel Function using scipy.integrate.quad
+proc integrate(f:proc(_: real):real, a: real, b: real): real {
+  use CTypes;
+  // get a c_ptr to a Chapel proc
+  var f_ptr = c_ptrTo(f):c_ptr(void);
+
+  // create a ctypes object from the function pointer
+  // another way to do this would be to support the pycapsule api in some form
+  var ctypes = interp.importModule("ctypes");
+  var ctypes_double = ctypes.get("c_double");
+  var cfunctype = ctypes.call("CFUNCTYPE", ctypes_double, ctypes_double);
+  var f_ptrPy = cfunctype(f_ptr:c_intptr);
+
+  // using the python representation of the function pointer,
+  // create a LowLevelCallable for scipy usage
+  var fPy = sp.call("LowLevelCallable", f_ptrPy,
+                    kwargs=["signature"=>"double (double)"]);
+
+  return spi.call("quad", fPy, a, b).call(real, "__getitem__", 0);
+}
+
+{
+  writeln("Integrating x**3, defined in Chapel");
+  export proc f(x: real): real do return x;
+  writeln(integrate(f, 0.0, 2.0));
+  writeln(integrate(f, 0.0, 4.0));
+  writeln(integrate(f, 0.0, 8.0));
+}

test/library/packages/Python/examples/scipy/integrateQuad.good

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+4.0
+64.0
+1024.0

test/library/packages/Python/examples/scipy/integrateQuad.skipif

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+#!/usr/bin/env bash
+
+# skip valgrind testing: if CHPL_TEST_VGRND_EXE is set and 'on'
+if [ -n "$CHPL_TEST_VGRND_EXE" ] && [ "$CHPL_TEST_VGRND_EXE" == "on" ]; then
+  echo "True"
+  exit 0
+fi
+
+FILE_DIR=$(cd $(dirname ${BASH_SOURCE[0]}) ; pwd)
+$FILE_DIR/../../skipIfAndInstallPackage.sh $FILE_DIR scipy