}
A = R.copy();
A.minusEquals(R);
Z = new Matrix(A.getRowDimension(), A.getColumnDimension());
try {
A.minusEquals(S);
errorCount = try_failure(errorCount,
"minusEquals conformance check... ",
"nonconformance not raised");
} catch (IllegalArgumentException e) {
try_success("minusEquals conformance check... ", "");