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program example_tridiagonal_matrix_cdp
use stdlib_linalg_constants, only: dp
use stdlib_specialmatrices, only: tridiagonal_cdp_type, tridiagonal, dense, spmv
implicit none
integer, parameter :: n = 5
type(tridiagonal_cdp_type) :: A
complex(dp) :: dl(n-1), dv(n), du(n-1)
complex(dp) :: x(n), y(n), y_dense(n)
integer :: i
complex(dp) :: alpha, beta
dl = [(cmplx(i,i, dp), i=1, n - 1)]
dv = [(cmplx(2*i,2*i, dp), i=1, n)]
du = [(cmplx(3*i,3*i, dp), i=1, n - 1)]
A = tridiagonal(dl, dv, du)
x = (1.0_dp, 0.0_dp)
y = (3.0_dp, -7.0_dp)
y_dense = (0.0_dp, 0.0_dp)
alpha = cmplx(2.0_dp, 3.0_dp)
beta = cmplx(-1.0_dp, 5.0_dp)
y_dense = alpha * matmul(dense(A), x) + beta * y
call spmv(A, x, y, alpha, beta)
print *, 'dense :', y_dense
print *, 'Tridiagonal :', y
end program example_tridiagonal_matrix_cdp
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