Changed name of rvalue function to roundvalues. Added modification to round down time step to nearest float with precision one less than hardware maximum. Avoids inadvertently exceeding the CFL due to binary representation of floating point number.

gprMax/input_cmds_singleuse.py

@@ -23,7 +23,7 @@ from psutil import virtual_memory
 from gprMax.constants import c, floattype
 from gprMax.exceptions import CmdInputError
 from gprMax.pml import PML, CFS
-from gprMax.utilities import rvalue, human_size
+from gprMax.utilities import roundvalue, rounddownmax, human_size
 from gprMax.waveforms import Waveform
 
 
@@ -114,9 +114,9 @@ def process_singlecmds(singlecmds, multicmds, G):
     tmp = [float(x) for x in singlecmds[cmd].split()]
     if len(tmp) != 3:
         raise CmdInputError(cmd + ' requires exactly three parameters')
-    G.nx = rvalue(tmp[0]/G.dx)
+    G.nx = roundvalue(tmp[0]/G.dx)
-    G.ny = rvalue(tmp[1]/G.dy)
+    G.ny = roundvalue(tmp[1]/G.dy)
-    G.nz = rvalue(tmp[2]/G.dz)
+    G.nz = roundvalue(tmp[2]/G.dz)
     if G.messages:
         print('Model domain: {:.3f} x {:.3f} x {:.3f} m ({:d} x {:d} x {:d} = {:.1f} Mcells)'.format(tmp[0], tmp[1], tmp[2], G.nx, G.ny, G.nz, (G.nx * G.ny * G.nz)/1e6))
         mem = (((G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 13 * np.dtype(floattype).itemsize + (G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 18) * 1.1) + 30e6
@@ -144,6 +144,10 @@ def process_singlecmds(singlecmds, multicmds, G):
             raise CmdInputError(cmd + ' requires input values of either 2D or 3D')
     else:
         G.dt = 1 / (c * np.sqrt((1 / G.dx) * (1 / G.dx) + (1 / G.dy) * (1 / G.dy) + (1 / G.dz) * (1 / G.dz)))
+
+    # Round down time step to nearest float with precision one less than hardware maximum. Avoids inadvertently exceeding the CFL due to binary representation of floating point number.
+    G.dt = rounddownmax(G.dt)
+
     if G.messages:
         print('Time step: {:.3e} secs'.format(G.dt))
 
@@ -171,7 +175,7 @@ def process_singlecmds(singlecmds, multicmds, G):
     if '.' in tmp or 'e' in tmp:
         if float(tmp) > 0:
             G.timewindow = float(tmp)
-            G.iterations = rvalue((float(tmp) / G.dt)) + 1
+            G.iterations = roundvalue((float(tmp) / G.dt)) + 1
         else:
             raise CmdInputError(cmd + ' must have a value greater than zero')
     # If number of iterations given
@@ -202,9 +206,9 @@ def process_singlecmds(singlecmds, multicmds, G):
         tmp = singlecmds[cmd].split()
         if len(tmp) != 3:
             raise CmdInputError(cmd + ' requires exactly three parameters')
-        G.srcstepx = rvalue(float(tmp[0])/G.dx)
+        G.srcstepx = roundvalue(float(tmp[0])/G.dx)
-        G.srcstepy = rvalue(float(tmp[1])/G.dy)
+        G.srcstepy = roundvalue(float(tmp[1])/G.dy)
-        G.srcstepz = rvalue(float(tmp[2])/G.dz)
+        G.srcstepz = roundvalue(float(tmp[2])/G.dz)
         if G.messages:
             print('All sources will step {:.3f}m, {:.3f}m, {:.3f}m for each model run.'.format(G.srcstepx * G.dx, G.srcstepy * G.dy, G.srcstepz * G.dz))
 
@@ -215,9 +219,9 @@ def process_singlecmds(singlecmds, multicmds, G):
         tmp = singlecmds[cmd].split()
         if len(tmp) != 3:
             raise CmdInputError(cmd + ' requires exactly three parameters')
-        G.rxstepx = rvalue(float(tmp[0])/G.dx)
+        G.rxstepx = roundvalue(float(tmp[0])/G.dx)
-        G.rxstepy = rvalue(float(tmp[1])/G.dy)
+        G.rxstepy = roundvalue(float(tmp[1])/G.dy)
-        G.rxstepz = rvalue(float(tmp[2])/G.dz)
+        G.rxstepz = roundvalue(float(tmp[2])/G.dz)
         if G.messages:
             print('All receivers will step {:.3f}m, {:.3f}m, {:.3f}m for each model run.'.format(G.rxstepx * G.dx, G.rxstepy * G.dy, G.rxstepz * G.dz))