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subroutine example_sparse_grid_04()
use Tasmanian
use, intrinsic :: iso_c_binding
implicit none
type(TasmanianSparseGrid) :: surrogate
integer :: prec, i
integer(C_INT), parameter :: num_inputs = 2
integer(C_INT), parameter :: num_outputs = 1
real(C_DOUBLE), dimension(:,:), allocatable :: points
real(C_DOUBLE), dimension(:,:), allocatable :: values
real(C_DOUBLE) :: x(2), y(1)
write(*,*) "-------------------------------------------------------------------------------------------------"
write(*,*) "Example 4: interpolate f(x,y) = exp(-x^2) * cos(y), using clenshaw-curtis iptotal rule"
write(*,*)
x = [ 0.3D-0, 0.7D-0 ]
do prec = 6, 12, 6
surrogate = TasmanianGlobalGrid(num_inputs, num_outputs, prec, &
tsg_type_iptotal, tsg_rule_clenshawcurtis)
allocate(points(num_inputs, surrogate%getNumNeeded()))
call surrogate%getNeededPoints(points(:,1))
allocate(values(num_outputs, surrogate%getNumNeeded()))
do i = 1, surrogate%getNumNeeded()
! fill the values with the model values at the points
values(1, i) = exp(-points(1,i)**2) * cos(points(2,i))
enddo
call surrogate%loadNeededValues(values(:,1))
! after the load call, the surrogate model is ready
! let y = surrogate(x)
call surrogate%evaluate(x, y)
write(*,"(A,i2)") " using polynomials of total degree up to: ", prec
write(*,"(A,i3,A)") " the grid has: ", &
surrogate%getNumPoints(), " points"
write(*,"(A,ES11.4)") " interpolant at (0.3,0.7): ", y(1)
write(*,"(A,ES11.4)") " error: ", &
abs(y(1) - exp(-x(1)**2) * cos(x(2)))
write(*,*)
call surrogate%release()
deallocate(points, values)
enddo
end subroutine
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