Initialise random number generator in _checkNonlinearity (#278)

* Initialise random number generator in `_checkNonlinearity`

* Add `initRand` to TACS.pyx

* Add `initRand` to TACS.pxd

* Adding virtual function for initRand to TACSVec class

---------

Co-authored-by: Tim Brooks <41971846+timryanb@users.noreply.github.com>

src/bpmat/KSM.h

@@ -108,6 +108,7 @@ class TACSVec : public TACSObject {
   // Additional useful member functions
   // ----------------------------------
   virtual void setRand(double lower = -1.0, double upper = 1.0) {}
+  virtual void initRand() {}
   virtual void applyBCs(TACSBcMap *map, TACSVec *vec = NULL) {}
   virtual void setBCs(TACSBcMap *map) {}
 };

tacs/TACS.pyx

@@ -712,6 +712,13 @@ cdef class Vec:
         self.ptr.setRand(lower, upper)
         return
 
+    def initRand(self):
+        """
+        Initialise random number generator
+        """
+        self.ptr.initRand()
+        return
+
     def getValues(self, np.ndarray[int, ndim=1] var):
         """
         Get the values from the given global indices
@@ -4227,4 +4234,4 @@ cdef class SpectralIntegrator:
         Compute the solution at the given time instance
         """
         self.ptr.computeSolutionAndDeriv(t, NULL, u.getBVecPtr(), NULL)
-        return
+        return

tacs/cpp_headers/TACS.pxd

@@ -115,6 +115,7 @@ cdef extern from "KSM.h":
         void copyValues(TACSVec *x)
         void axpby(TacsScalar alpha, TacsScalar beta, TACSVec *x)
         void zeroEntries()
+        void initRand()
         void setRand(double lower, double upper)
 
     cdef cppclass TACSMat(TACSObject):

tacs/pytacs.py

@@ -836,6 +836,7 @@ def _checkNonlinearity(self) -> bool:
         self.assembler.assembleRes(res0)
 
         # Evaluate r(u) - r(0)
+        state.initRand()
         state.setRand()
         self.setBCsInVec(state)
         self.assembler.setVariables(state, state, state)