how to transfer an initial field before solve ax=b

[ztdepztdep]

how to transfer an initial field before solve ax=b

[pratikvn]

Do you mean the initial solution, x ? If you have a pointer (say dx) to the data on exec which can be either ReferenceExecutor or CudaExecutor, then you can just do:
(Updated):

auto x = gko::matrix::Dense<ValueType>::create(exec, 
                                               gko::dim<2>(num_elems, 1), 
                                               gko::array<ValueType>::view(exec, num_elems, dx),
                                               stride);

This will not allocate new memory, but use the data that dx points to and which is of size num_elems

[ztdepztdep]

/home/ztdep/lib/ginkgo/include/ginkgo/core/base/polymorphic_object.hpp(737): error: no instance of constructor "gko::matrix::Dense::Dense [with ValueType=double]" matches the argument list
argument types are: (const std::shared_ptrgko::Executor, gko::dim<2UL, gko::size_type>, gko::array)
detected during instantiation of "std::unique_ptr<ConcreteType, std::default_delete> gko::EnableCreateMethod::create(Args &&...) [with ConcreteType=gko::matrix::Dense, Args=<const std::shared_ptrgko::Executor &, gko::dim<2UL, gko::size_type>, gko::array>]"

[upsj]

There is a parameter missing:

auto x = gko::matrix::Dense<ValueType>::create(exec, 
                                               gko::dim<2>(num_elems, 1), 
                                               gko::array<ValueType>::view(exec, num_elems, dx),
                                               stride);