Improve error message during setup of TXL or CPL

src/spicelib/devices/cpl/cplsetup.c

@@ -832,7 +832,10 @@ Gaussian_Elimination2(int dims, int type)
 				max = ABS(A[j][i]);
 			}
 		if (max < epsilon) {
-			fprintf(stderr, " can not choose a pivot (misc)\n");
+			fprintf(stderr, "\nError: Gaussian elimination (misc) fails during setup of CPL\n");
+			fprintf(stderr, "    All matrix elements are less than %e, \n", epsilon);
+			fprintf(stderr, "    thus cannot choose a pivot.\n");
+			fprintf(stderr, "    Please check your model parameters.\n");
 			controlled_exit(EXIT_FAILURE);
 		}
 		if (imax != i)
@@ -1767,7 +1770,10 @@ Gaussian_Elimination(int dims)
 				max = ABS(At[j][i]);
 			}
 		if (max < epsi_mult) {
-			fprintf(stderr, " can not choose a pivot (mult)\n");
+			fprintf(stderr, "\nError: Gaussian elimination (mult) fails during setup of CPL\n");
+			fprintf(stderr, "    All matrix elements are less than %e, \n", epsi_mult);
+			fprintf(stderr, "    thus cannot choose a pivot.\n");
+			fprintf(stderr, "    Please check your model parameters.\n");
 			controlled_exit(EXIT_FAILURE);
 		}
 		if (imax != i)

src/spicelib/devices/txl/txlsetup.c

@@ -545,7 +545,10 @@ Gaussian_Elimination1(int dims)
 	    max = ABS(A[j][i]);
 	 } 
       if (max < epsi) {
-         fprintf(stderr, " can not choose a pivot \n");
+          fprintf(stderr, "\nError: Gaussian elimination fails during setup of TXL\n");
+          fprintf(stderr, "    All matrix elements are less than %e, \n", epsi);
+          fprintf(stderr, "    thus cannot choose a pivot.\n");
+          fprintf(stderr, "    Please check your model parameters.\n");
          controlled_exit(EXIT_FAILURE);
       }
       if (imax != i)
@@ -905,7 +908,10 @@ Gaussian_Elimination2(int dims)
             max = ABS(AA[j][i]);
          }
       if (max < epsi2) {
-         fprintf(stderr, " can not choose a pivot \n");
+         fprintf(stderr, "\nError: Gaussian elimination fails during setup of TXL\n");
+         fprintf(stderr, "    All matrix elements are less than %e, \n", epsi2);
+         fprintf(stderr, "    thus cannot choose a pivot.\n");
+         fprintf(stderr, "    Please check your model parameters.\n");
          controlled_exit(EXIT_FAILURE);
       }
       if (imax != i)