add alternate random field generator

bfps/tools.py

@@ -143,6 +143,19 @@ def generate_data_3D(
     a[ii] = 0
     return a
 
+
+def generate_random_discontinuous_data_3D(
+        n0, n1, n2,
+        dtype = np.complex128,
+        p = 1.5,
+        amplitude = 0.5):
+    """returns the Fourier representation of a random field.
+    """
+    assert(n0 % 2 == 0 and n1 % 2 == 0 and n2 % 2 == 0)
+    a = np.random.randn(n1, n0, n2)
+    b = np.fft.rfftn(a).astype(dtype)
+    return b
+
 def randomize_phases(v):
     """randomize the phases of an FFTW complex field.