! D01JAF Example Program Text
! Mark 28.4 Release. NAG Copyright 2022.
Module d01jafe_mod
! D01JAF Example Program Module:
! Parameters and User-defined Routines
! .. Use Statements ..
Use nag_library, Only: nag_wp, x02amf
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: f
! .. Parameters ..
Integer, Parameter, Public :: nout = 6
Contains
Function f(ndim,x)
! .. Function Return Value ..
Real (Kind=nag_wp) :: f
! .. Scalar Arguments ..
Integer, Intent (In) :: ndim
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (In) :: x(ndim)
! .. Local Scalars ..
Real (Kind=nag_wp) :: a, rho
! .. Intrinsic Procedures ..
Intrinsic :: abs, sqrt
! .. Executable Statements ..
rho = x(1)
a = (1.0E0_nag_wp-rho)*(1.0E0_nag_wp+rho)
If (abs(a)>=x02amf()) Then
f = 1.0E0_nag_wp/sqrt(a)
Else
f = 0.0E0_nag_wp
End If
Return
End Function f
End Module d01jafe_mod
Program d01jafe
! D01JAF Example Main Program
! .. Use Statements ..
Use d01jafe_mod, Only: f, nout
Use nag_library, Only: d01jaf, nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Local Scalars ..
Real (Kind=nag_wp) :: epsa, epsr, esterr, radius, relest, &
result
Integer :: icoord, ifail, method, ndim, nevals
! .. Executable Statements ..
Write (nout,*) 'D01JAF Example Program Results'
radius = 1.0E0_nag_wp
method = 0
icoord = 1
epsa = 0.0E0_nag_wp
epsr = 0.5E-4_nag_wp
test: Do ndim = 2, 4, 2
ifail = -1
Call d01jaf(f,ndim,radius,epsa,epsr,method,icoord,result,esterr, &
nevals,ifail)
Select Case (ifail)
Case (:-1)
Exit test
Case (0:3)
relest = esterr/result
Write (nout,*)
Write (nout,99999) 'Dimension of the sphere =', ndim
Write (nout,99998) 'Requested relative tolerance =', epsr
Write (nout,99997) 'Approximation to the integral =', result
Write (nout,99999) 'No. of function evaluations =', nevals
Write (nout,99998) 'Estimated relative error =', relest
End Select
End Do test
99999 Format (1X,A,I5)
99998 Format (1X,A,E9.2)
99997 Format (1X,A,F9.5)
End Program d01jafe