Merge pull request #145 from roryyorke/rory/static-ss-to-tf · python-control/python-control@05d6bc5
@@ -1098,40 +1098,48 @@ def _convertToTransferFunction(sys, **kw):
1098109810991099return sys
11001100elif isinstance(sys, StateSpace):
1101-try:
1102-from slycot import tb04ad
1103-if len(kw):
1104-raise TypeError(
1105-"If sys is a StateSpace, " +
1106-"_convertToTransferFunction cannot take keywords.")
1107-1108-# Use Slycot to make the transformation
1109-# Make sure to convert system matrices to numpy arrays
1110-tfout = tb04ad(sys.states, sys.inputs, sys.outputs, array(sys.A),
1111-array(sys.B), array(sys.C), array(sys.D), tol1=0.0)
1112-1113-# Preallocate outputs.
1114-num = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
1115-den = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
1116-1117-for i in range(sys.outputs):
1118-for j in range(sys.inputs):
1119-num[i][j] = list(tfout[6][i, j, :])
1120-# Each transfer function matrix row
1121-# has a common denominator.
1122-den[i][j] = list(tfout[5][i, :])
1123-# print(num)
1124-# print(den)
1125-except ImportError:
1126-# If slycot is not available, use signal.lti (SISO only)
1127-if (sys.inputs != 1 or sys.outputs != 1):
1128-raise TypeError("No support for MIMO without slycot")
1129-1130-lti_sys = lti(sys.A, sys.B, sys.C, sys.D)
1131-num = squeeze(lti_sys.num)
1132-den = squeeze(lti_sys.den)
1133-# print(num)
1134-# print(den)
1101+1102+if 0==sys.states:
1103+# Slycot doesn't like static SS->TF conversion, so handle
1104+# it first. Can't join this with the no-Slycot branch,
1105+# since that doesn't handle general MIMO systems
1106+num = [[[sys.D[i,j]] for j in range(sys.inputs)] for i in range(sys.outputs)]
1107+den = [[[1.] for j in range(sys.inputs)] for i in range(sys.outputs)]
1108+else:
1109+try:
1110+from slycot import tb04ad
1111+if len(kw):
1112+raise TypeError(
1113+"If sys is a StateSpace, " +
1114+"_convertToTransferFunction cannot take keywords.")
1115+1116+# Use Slycot to make the transformation
1117+# Make sure to convert system matrices to numpy arrays
1118+tfout = tb04ad(sys.states, sys.inputs, sys.outputs, array(sys.A),
1119+array(sys.B), array(sys.C), array(sys.D), tol1=0.0)
1120+1121+# Preallocate outputs.
1122+num = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
1123+den = [[[] for j in range(sys.inputs)] for i in range(sys.outputs)]
1124+1125+for i in range(sys.outputs):
1126+for j in range(sys.inputs):
1127+num[i][j] = list(tfout[6][i, j, :])
1128+# Each transfer function matrix row
1129+# has a common denominator.
1130+den[i][j] = list(tfout[5][i, :])
1131+# print(num)
1132+# print(den)
1133+except ImportError:
1134+# If slycot is not available, use signal.lti (SISO only)
1135+if (sys.inputs != 1 or sys.outputs != 1):
1136+raise TypeError("No support for MIMO without slycot")
1137+1138+lti_sys = lti(sys.A, sys.B, sys.C, sys.D)
1139+num = squeeze(lti_sys.num)
1140+den = squeeze(lti_sys.den)
1141+# print(num)
1142+# print(den)
1135114311361144return TransferFunction(num, den, sys.dt)
11371145