Created testInstallation.py script

examples/testInstallation.py

+# First make sure OpenMM is installed.
+
+import sys
+try:
+    from simtk.openmm.app import *
+    from simtk.openmm import *
+    from simtk.unit import *
+except ImportError as err:
+    print "Failed to import OpenMM packages:", err.message
+    print "Make sure OpenMM is installed and the library path is set correctly."
+    sys.exit()
+
+# Create a System for the tests.
+
+pdb = PDBFile('input.pdb')
+forcefield = ForceField('amber99sb.xml', 'tip3p.xml')
+system = forcefield.createSystem(pdb.topology, nonbondedMethod=PME, nonbondedCutoff=1*nanometer, constraints=HBonds)
+
+# List all installed platforms and compute forces with each one.
+
+numPlatforms = Platform.getNumPlatforms()
+print "There are", numPlatforms, "Platforms available:"
+print
+forces = [None]*numPlatforms
+for i in range(numPlatforms):
+    platform = Platform.getPlatform(i)
+    print i, platform.getName(),
+    integrator = LangevinIntegrator(300*kelvin, 1/picosecond, 0.002*picoseconds)
+    simulation = Simulation(pdb.topology, system, integrator)
+    simulation.context.setPositions(pdb.positions)
+    try:
+        forces[i] = simulation.context.getState(getForces=True).getForces()
+        print "- Successfully computed forces"
+    except:
+        print "- Error computing forces"
+
+# See how well the platforms agree.
+
+print
+print "Maximum difference in forces between platforms:"
+print
+for i in range(numPlatforms):
+    for j in range(i):
+        if forces[i] is not None and forces[j] is not None:
+            maxError = 0.0
+            for f1, f2 in zip(forces[i], forces[j]):
+                d = f1-f2
+                error = sqrt((d[0]*d[0]+d[1]*d[1]+d[2]*d[2])/(f1[0]*f1[0]+f1[1]*f1[1]+f1[2]*f1[2]))
+                maxError = max(maxError, error)
+            print "%s vs. %s: %g" % (Platform.getPlatform(j).getName(), Platform.getPlatform(i).getName(), maxError)