Chebyshev1GradientEval

Evaluate gradient of Chebyshev1 polynomials.

Interface 1

INTERFACE
  MODULE PURE FUNCTION Chebyshev1GradientEval(n, x) RESULT(ans)
    INTEGER(I4B), INTENT(IN) :: n
    REAL(DFP), INTENT(IN) :: x
    REAL(DFP) :: ans
  END FUNCTION Chebyshev1GradientEval
END INTERFACE

Interface 2

INTERFACE
  MODULE PURE FUNCTION Chebyshev1GradientEval(n, x) RESULT(ans)
    INTEGER(I4B), INTENT(IN) :: n
    REAL(DFP), INTENT(IN) :: x(:)
    REAL(DFP) :: ans(1:SIZE(x))
  END FUNCTION Chebyshev1GradientEval
END INTERFACE

Examples

️܀ See example

program main
  use easifembase
  implicit none
  integer( i4b ) :: n
  real( dfp ) :: ans, x, exact
  real( dfp ), parameter :: tol=1.0E-10
  n = 4
  x = -1.0_DFP; call callme
  exact = 32.0 * x**3 - 16.0*x
  call ok( SOFTEQ(ans, exact, tol ))
  x = -0.5_DFP; call callme
  exact = 32.0 * x**3 - 16.0*x
  call ok( SOFTEQ(ans, exact, tol ))
  x = 0.0_DFP; call callme
  exact = 32.0 * x**3 - 16.0*x
  call ok( SOFTEQ(ans, exact, tol ))
  x = 0.5_DFP; call callme
  exact = 32.0 * x**3 - 16.0*x
  call ok( SOFTEQ(ans, exact, tol ))
  x = +1.0_DFP; call callme
  exact = 32.0 * x**3 - 16.0*x
  call ok( SOFTEQ(ans, exact, tol ))
  contains
  subroutine callme
    ans= Chebyshev1GradientEval( n=n, x=x )
  end subroutine callme
end program main

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