diff -r cb4bd6829f52 include/petscmath.h
--- a/include/petscmath.h	Wed Jun 28 17:38:54 2006 -0400
+++ b/include/petscmath.h	Fri Jun 30 11:28:20 2006 +0200
@@ -27,9 +27,9 @@ extern  MPI_Datatype PETSC_DLLEXPORT MPI
 #define PetscExpPassiveScalar(a) PetscExpScalar()
 
 #if defined(PETSC_USE_COMPLEX)
-
-/*
-   PETSc now only supports std::complex
+#if defined(PETSC_CLANGUAGE_CXX)
+/*
+   C++ support of complex numbers: Original support
 */
 #include <complex>
 
@@ -52,6 +52,34 @@ extern  MPI_Datatype PETSC_DLLEXPORT MPI
 #define PetscCosScalar(a)   std::cos(a)
 
 typedef std::complex<double> PetscScalar;
+#else
+#include <complex.h>
+
+/* 
+   C support of complex numbers: Warning it needs a 
+   C90 compliant compiler to work...
+ */
+
+extern  MPI_Datatype PETSC_DLLEXPORT MPIU_COMPLEX;
+#define MPIU_SCALAR         MPIU_COMPLEX
+#if defined(PETSC_USE_MAT_SINGLE)
+#define MPIU_MATSCALAR        ??Notdone
+#else
+#define MPIU_MATSCALAR      MPIU_COMPLEX
+#endif
+
+#define PetscRealPart(a)        creal(a)
+#define PetscImaginaryPart(a)   cimag(a)
+#define PetscAbsScalar(a)   cabs(a)
+#define PetscConj(a)        conj(a)
+#define PetscSqrtScalar(a)  csqrt(a)
+#define PetscPowScalar(a,b) cpow(a,b)
+#define PetscExpScalar(a)   cexp(a)
+#define PetscSinScalar(a)   csin(a)
+#define PetscCosScalar(a)   ccos(a)
+
+typedef double complex PetscScalar;
+#endif
 
 /* Compiling for real numbers only */
 #else
diff -r cb4bd6829f52 python/PETSc/utilities/languages.py
--- a/python/PETSc/utilities/languages.py	Wed Jun 28 17:38:54 2006 -0400
+++ b/python/PETSc/utilities/languages.py	Fri Jun 30 11:28:20 2006 +0200
@@ -69,8 +69,8 @@ class Configure(config.base.Configure):
     self.clanguage = self.framework.argDB['with-clanguage'].upper().replace('+','x').replace('X','x')
     if not self.clanguage in ['C', 'Cxx']:
       raise RuntimeError('Invalid C language specified: '+str(self.clanguage))
-    if self.scalartype == 'complex':
-      self.clanguage = 'Cxx'
+#    if self.scalartype == 'complex':
+#      self.clanguage = 'Cxx'
     if self.clanguage == 'C' and not self.framework.argDB['with-c++-support'] and not self.packagesHaveCxx():
       self.framework.argDB['with-cxx'] = '0'
       self.framework.logPrint('Turning off C++ support')
diff -r cb4bd6829f52 src/mat/impls/aij/mpi/mpiaij.c
--- a/src/mat/impls/aij/mpi/mpiaij.c	Wed Jun 28 17:38:54 2006 -0400
+++ b/src/mat/impls/aij/mpi/mpiaij.c	Fri Jun 30 11:28:20 2006 +0200
@@ -2285,7 +2285,7 @@ EXTERN_C_BEGIN
 EXTERN_C_BEGIN
 #undef __FUNCT__  
 #define __FUNCT__ "MatMPIAIJSetPreallocationCSR_MPIAIJ"
-PetscErrorCode PETSCMAT_DLLEXPORT MatMPIAIJSetPreallocationCSR_MPIAIJ(Mat B,const PetscInt I[],const PetscInt J[],const PetscScalar v[])
+PetscErrorCode PETSCMAT_DLLEXPORT MatMPIAIJSetPreallocationCSR_MPIAIJ(Mat B,const PetscInt Ii[],const PetscInt J[],const PetscScalar v[])
 {
   PetscInt       m,cstart, cend,j,nnz,i,d; 
   PetscInt       *d_nnz,*o_nnz,nnz_max = 0,rstart,ii;
@@ -2294,7 +2294,7 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatMPI
   PetscErrorCode ierr;
 
   PetscFunctionBegin;
-  if (I[0]) SETERRQ1(PETSC_ERR_ARG_OUTOFRANGE,"I[0] must be 0 it is %D",I[0]);
+  if (Ii[0]) SETERRQ1(PETSC_ERR_ARG_OUTOFRANGE,"Ii[0] must be 0 it is %D",Ii[0]);
 
   B->rmap.bs = B->cmap.bs = 1;
   ierr = PetscMapInitialize(B->comm,&B->rmap);CHKERRQ(ierr);
@@ -2308,8 +2308,8 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatMPI
   o_nnz = d_nnz + m;
 
   for (i=0; i<m; i++) {
-    nnz     = I[i+1]- I[i];
-    JJ      = J + I[i];
+    nnz     = Ii[i+1]- Ii[i];
+    JJ      = J + Ii[i];
     nnz_max = PetscMax(nnz_max,nnz);
     if (nnz < 0) SETERRQ2(PETSC_ERR_ARG_OUTOFRANGE,"Local row %D has a negative %D number of columns",i,nnz);
     for (j=0; j<nnz; j++) {
@@ -2336,8 +2336,8 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatMPI
   ierr = MatSetOption(B,MAT_COLUMNS_SORTED);CHKERRQ(ierr);
   for (i=0; i<m; i++) {
     ii   = i + rstart;
-    nnz  = I[i+1]- I[i];
-    ierr = MatSetValues_MPIAIJ(B,1,&ii,nnz,J+I[i],values+(v ? I[i] : 0),INSERT_VALUES);CHKERRQ(ierr);
+    nnz  = Ii[i+1]- Ii[i];
+    ierr = MatSetValues_MPIAIJ(B,1,&ii,nnz,J+Ii[i],values+(v ? Ii[i] : 0),INSERT_VALUES);CHKERRQ(ierr);
   }
   ierr = MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
   ierr = MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
@@ -2880,7 +2880,7 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatMer
 PetscErrorCode PETSCMAT_DLLEXPORT MatMerge(MPI_Comm comm,Mat inmat,PetscInt n,MatReuse scall,Mat *outmat)
 {
   PetscErrorCode ierr;
-  PetscInt       m,N,i,rstart,nnz,I,*dnz,*onz;
+  PetscInt       m,N,i,rstart,nnz,Ii,*dnz,*onz;
   PetscInt       *indx;
   PetscScalar    *values;
 
@@ -2915,8 +2915,8 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatMer
 
   for (i=0;i<m;i++) {
     ierr = MatGetRow_SeqAIJ(inmat,i,&nnz,&indx,&values);CHKERRQ(ierr);
-    I    = i + rstart;
-    ierr = MatSetValues(*outmat,1,&I,nnz,indx,values,INSERT_VALUES);CHKERRQ(ierr);
+    Ii    = i + rstart;
+    ierr = MatSetValues(*outmat,1,&Ii,nnz,indx,values,INSERT_VALUES);CHKERRQ(ierr);
     ierr = MatRestoreRow_SeqAIJ(inmat,i,&nnz,&indx,&values);CHKERRQ(ierr);
   }
   ierr = MatDestroy(inmat);CHKERRQ(ierr);
diff -r cb4bd6829f52 src/mat/impls/aij/seq/aij.c
--- a/src/mat/impls/aij/seq/aij.c	Wed Jun 28 17:38:54 2006 -0400
+++ b/src/mat/impls/aij/seq/aij.c	Fri Jun 30 11:28:20 2006 +0200
@@ -2787,7 +2787,7 @@ EXTERN_C_BEGIN
 EXTERN_C_BEGIN
 #undef  __FUNCT__
 #define __FUNCT__  "MatSeqAIJSetPreallocationCSR_SeqAIJ"
-PetscErrorCode PETSCMAT_DLLEXPORT MatSeqAIJSetPreallocationCSR_SeqAIJ(Mat B,const PetscInt I[],const PetscInt J[],const PetscScalar v[])
+PetscErrorCode PETSCMAT_DLLEXPORT MatSeqAIJSetPreallocationCSR_SeqAIJ(Mat B,const PetscInt Ii[],const PetscInt J[],const PetscScalar v[])
 {
   PetscInt       i;
   PetscInt       m,n;
@@ -2799,12 +2799,12 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatSeq
   PetscFunctionBegin;
   ierr = MatGetSize(B, &m, &n);CHKERRQ(ierr);
 
-  if (I[0]) {
-    SETERRQ1(PETSC_ERR_ARG_OUTOFRANGE, "I[0] must be 0 it is %D", I[0]);
+  if (Ii[0]) {
+    SETERRQ1(PETSC_ERR_ARG_OUTOFRANGE, "Ii[0] must be 0 it is %D", Ii[0]);
   }
   ierr = PetscMalloc((m+1) * sizeof(PetscInt), &nnz);CHKERRQ(ierr);
   for(i = 0; i < m; i++) {
-    nz     = I[i+1]- I[i];
+    nz     = Ii[i+1]- Ii[i];
     nz_max = PetscMax(nz_max, nz);
     if (nz < 0) {
       SETERRQ2(PETSC_ERR_ARG_OUTOFRANGE, "Local row %D has a negative number of columns %D", i, nnz);
@@ -2824,8 +2824,8 @@ PetscErrorCode PETSCMAT_DLLEXPORT MatSeq
   ierr = MatSetOption(B,MAT_COLUMNS_SORTED);CHKERRQ(ierr);
 
   for(i = 0; i < m; i++) {
-    nz  = I[i+1] - I[i];
-    ierr = MatSetValues_SeqAIJ(B, 1, &i, nz, J+I[i], values + (v ? I[i] : 0), INSERT_VALUES);CHKERRQ(ierr);
+    nz  = Ii[i+1] - Ii[i];
+    ierr = MatSetValues_SeqAIJ(B, 1, &i, nz, J+Ii[i], values + (v ? Ii[i] : 0), INSERT_VALUES);CHKERRQ(ierr);
   }
 
   ierr = MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
diff -r cb4bd6829f52 src/mat/impls/baij/mpi/mpibaij.c
--- a/src/mat/impls/baij/mpi/mpibaij.c	Wed Jun 28 17:38:54 2006 -0400
+++ b/src/mat/impls/baij/mpi/mpibaij.c	Fri Jun 30 11:28:20 2006 +0200
@@ -2103,7 +2103,7 @@ EXTERN_C_END
 
 #undef __FUNCT__  
 #define __FUNCT__ "MatMPIBAIJSetPreallocationCSR_MPIBAIJ"
-PetscErrorCode MatMPIBAIJSetPreallocationCSR_MPIBAIJ(Mat B,PetscInt bs,const PetscInt I[],const PetscInt J[],const PetscScalar v[])
+PetscErrorCode MatMPIBAIJSetPreallocationCSR_MPIBAIJ(Mat B,PetscInt bs,const PetscInt Ii[],const PetscInt J[],const PetscScalar v[])
 {
   Mat_MPIBAIJ    *baij = (Mat_MPIBAIJ*)B->data;
   PetscInt       m = B->rmap.n/bs,cstart = baij->cstartbs, cend = baij->cendbs,j,nnz,i,d; 
@@ -2114,14 +2114,14 @@ PetscErrorCode MatMPIBAIJSetPreallocatio
 
   PetscFunctionBegin;
 #if defined(PETSC_OPT_g)
-  if (I[0]) SETERRQ1(PETSC_ERR_ARG_RANGE,"I[0] must be 0 it is %D",I[0]);
+  if (Ii[0]) SETERRQ1(PETSC_ERR_ARG_RANGE,"Ii[0] must be 0 it is %D",Ii[0]);
 #endif
   ierr  = PetscMalloc((2*m+1)*sizeof(PetscInt),&d_nnz);CHKERRQ(ierr);
   o_nnz = d_nnz + m;
 
   for (i=0; i<m; i++) {
-    nnz     = I[i+1]- I[i];
-    JJ      = J + I[i];
+    nnz     = Ii[i+1]- Ii[i];
+    JJ      = J + Ii[i];
     nnz_max = PetscMax(nnz_max,nnz);
 #if defined(PETSC_OPT_g)
     if (nnz < 0) SETERRQ1(PETSC_ERR_ARG_RANGE,"Local row %D has a negative %D number of columns",i,nnz);
@@ -2150,8 +2150,8 @@ PetscErrorCode MatMPIBAIJSetPreallocatio
   ierr = MatSetOption(B,MAT_COLUMNS_SORTED);CHKERRQ(ierr);
   for (i=0; i<m; i++) {
     ii   = i + rstart;
-    nnz  = I[i+1]- I[i];
-    ierr = MatSetValuesBlocked_MPIBAIJ(B,1,&ii,nnz,J+I[i],values+(v ? I[i] : 0),INSERT_VALUES);CHKERRQ(ierr);
+    nnz  = Ii[i+1]- Ii[i];
+    ierr = MatSetValuesBlocked_MPIBAIJ(B,1,&ii,nnz,J+Ii[i],values+(v ? Ii[i] : 0),INSERT_VALUES);CHKERRQ(ierr);
   }
   ierr = MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
   ierr = MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
diff -r cb4bd6829f52 src/sys/objects/pinit.c
--- a/src/sys/objects/pinit.c	Wed Jun 28 17:38:54 2006 -0400
+++ b/src/sys/objects/pinit.c	Fri Jun 30 11:28:20 2006 +0200
@@ -449,9 +449,15 @@ PetscErrorCode PETSC_DLLEXPORT PetscInit
      are not called; at least on IRIX.
   */
   {
+#ifdef PETSC_CLANGUAGE_CXX
     PetscScalar ic(0.0,1.0);
     PETSC_i = ic; 
-  }
+#else
+    PetscScalar ic;
+    ic = 1.I;
+    PETSC_i = ic;
+  }
+#endif
   ierr = MPI_Type_contiguous(2,MPIU_REAL,&MPIU_COMPLEX);CHKERRQ(ierr);
   ierr = MPI_Type_commit(&MPIU_COMPLEX);CHKERRQ(ierr);
   ierr = MPI_Op_create(PetscSum_Local,1,&PetscSum_Op);CHKERRQ(ierr);
diff -r cb4bd6829f52 src/sys/utils/sorti.c
--- a/src/sys/utils/sorti.c	Wed Jun 28 17:38:54 2006 -0400
+++ b/src/sys/utils/sorti.c	Fri Jun 30 11:28:20 2006 +0200
@@ -137,7 +137,7 @@ static PetscErrorCode PetscSortIntWithAr
 
 .seealso: PetscSortReal(), PetscSortIntPermutation(), PetscSortInt()
 @*/
-PetscErrorCode PETSC_DLLEXPORT PetscSortIntWithArray(PetscInt n,PetscInt i[],PetscInt I[])
+PetscErrorCode PETSC_DLLEXPORT PetscSortIntWithArray(PetscInt n,PetscInt i[],PetscInt Ii[])
 {
   PetscErrorCode ierr;
   PetscInt j,k,tmp,ik;
@@ -148,13 +148,13 @@ PetscErrorCode PETSC_DLLEXPORT PetscSort
       ik = i[k];
       for (j=k+1; j<n; j++) {
 	if (ik > i[j]) {
-	  SWAP2(i[k],i[j],I[k],I[j],tmp);
-	  ik = i[k];
-	}
-      }
-    }
-  } else {
-    ierr = PetscSortIntWithArray_Private(i,I,n-1);CHKERRQ(ierr);
+	  SWAP2(i[k],i[j],Ii[k],Ii[j],tmp);
+	  ik = i[k];
+	}
+      }
+    }
+  } else {
+    ierr = PetscSortIntWithArray_Private(i,Ii,n-1);CHKERRQ(ierr);
   }
   PetscFunctionReturn(0);
 }
@@ -211,7 +211,7 @@ static PetscErrorCode PetscSortIntWithSc
 
 .seealso: PetscSortReal(), PetscSortIntPermutation(), PetscSortInt(), PetscSortIntWithArray()
 @*/
-PetscErrorCode PETSC_DLLEXPORT PetscSortIntWithScalarArray(PetscInt n,PetscInt i[],PetscScalar I[])
+PetscErrorCode PETSC_DLLEXPORT PetscSortIntWithScalarArray(PetscInt n,PetscInt i[],PetscScalar Ii[])
 {
   PetscErrorCode ierr;
   PetscInt       j,k,tmp,ik;
@@ -223,15 +223,15 @@ PetscErrorCode PETSC_DLLEXPORT PetscSort
       ik = i[k];
       for (j=k+1; j<n; j++) {
 	if (ik > i[j]) {
-	  SWAP2IntScalar(i[k],i[j],I[k],I[j],tmp,stmp);
-	  ik = i[k];
-	}
-      }
-    }
-  } else {
-    ierr = PetscSortIntWithScalarArray_Private(i,I,n-1);CHKERRQ(ierr);
-  }
-  PetscFunctionReturn(0);
-}
-
-
+	  SWAP2IntScalar(i[k],i[j],Ii[k],Ii[j],tmp,stmp);
+	  ik = i[k];
+	}
+      }
+    }
+  } else {
+    ierr = PetscSortIntWithScalarArray_Private(i,Ii,n-1);CHKERRQ(ierr);
+  }
+  PetscFunctionReturn(0);
+}
+
+