Added probing.py

demos/probing.py

+# -*- coding: utf-8 -*-
+
+from nifty import Field, RGSpace, DiagonalProberMixin, TraceProberMixin,\
+                  Prober, DiagonalOperator
+
+
+class DiagonalProber(DiagonalProberMixin, Prober):
+    pass
+
+
+class MultiProber(DiagonalProberMixin, TraceProberMixin, Prober):
+    pass
+
+
+x = RGSpace((8, 8))
+
+f = Field.from_random(domain=x, random_type='normal')
+diagOp = DiagonalOperator(domain=x, diagonal=f)
+
+diagProber = DiagonalProber(domain=x)
+diagProber(diagOp)
+print (f - diagProber.diagonal).norm()
+
+multiProber = MultiProber(domain=x)
+multiProber(diagOp)
+print (f - multiProber.diagonal).norm()
+print f.sum() - multiProber.trace
+
+
+