NAG Library Function Document
nag_ode_bvp_coll_nlin_solve (d02tlc)
1 Purpose
nag_ode_bvp_coll_nlin_solve (d02tlc) solves a general two-point boundary value problem for a nonlinear mixed order system of ordinary differential equations.
2 Specification
#include <nag.h> |
#include <nagd02.h> |
void |
nag_ode_bvp_coll_nlin_solve (
void |
(*ffun)(double x,
const double y[],
Integer neq,
const Integer m[],
double f[],
Nag_Comm *comm),
|
|
void |
(*fjac)(double x,
const double y[],
Integer neq,
const Integer m[],
double dfdy[],
Nag_Comm *comm),
|
|
void |
(*gafun)(const double ya[],
Integer neq,
const Integer m[],
Integer nlbc,
double ga[],
Nag_Comm *comm),
|
|
void |
(*gbfun)(const double yb[],
Integer neq,
const Integer m[],
Integer nrbc,
double gb[],
Nag_Comm *comm),
|
|
void |
(*guess)(double x,
Integer neq,
const Integer m[],
double y[],
double dym[],
Nag_Comm *comm),
|
|
double rcomm[],
Integer icomm[],
Nag_Comm *comm,
NagError *fail) |
|
3 Description
nag_ode_bvp_coll_nlin_solve (d02tlc) and its associated functions (
nag_ode_bvp_coll_nlin_setup (d02tvc),
nag_ode_bvp_coll_nlin_contin (d02txc),
nag_ode_bvp_coll_nlin_interp (d02tyc) and
nag_ode_bvp_coll_nlin_diag (d02tzc)) solve the two-point boundary value problem for a nonlinear mixed order system of ordinary differential equations
over an interval
subject to
(
) nonlinear boundary conditions at
and
(
) nonlinear boundary conditions at
, where
. Note that
is the
th derivative of the
th solution component. Hence
. The left boundary conditions at
are defined as
and the right boundary conditions at
as
where
and
First,
nag_ode_bvp_coll_nlin_setup (d02tvc) must be called to specify the initial mesh, error requirements and other details. Note that the error requirements apply only to the solution components
and that no error control is applied to derivatives of solution components. (If error control is required on derivatives then the system must be reduced in order by introducing the derivatives whose error is to be controlled as new variables. See
Section 9 in nag_ode_bvp_coll_nlin_setup (d02tvc).) Then, nag_ode_bvp_coll_nlin_solve (d02tlc) can be used to solve the boundary value problem. After successful computation,
nag_ode_bvp_coll_nlin_diag (d02tzc) can be used to ascertain details about the final mesh and other details of the solution procedure, and
nag_ode_bvp_coll_nlin_interp (d02tyc) can be used to compute the approximate solution anywhere on the interval
.
A description of the numerical technique used in nag_ode_bvp_coll_nlin_solve (d02tlc) is given in
Section 3 in nag_ode_bvp_coll_nlin_setup (d02tvc).
nag_ode_bvp_coll_nlin_solve (d02tlc) can also be used in the solution of a series of problems, for example in performing continuation, when the mesh used to compute the solution of one problem is to be used as the initial mesh for the solution of the next related problem.
nag_ode_bvp_coll_nlin_contin (d02txc) should be used in between calls to nag_ode_bvp_coll_nlin_solve (d02tlc) in this context.
See
Section 9 in nag_ode_bvp_coll_nlin_setup (d02tvc) for details of how to solve boundary value problems of a more general nature.
The functions are based on modified versions of the codes COLSYS and COLNEW (see
Ascher et al. (1979) and
Ascher and Bader (1987)). A comprehensive treatment of the numerical solution of boundary value problems can be found in
Ascher et al. (1988) and
Keller (1992).
4 References
Ascher U M and Bader G (1987) A new basis implementation for a mixed order boundary value ODE solver SIAM J. Sci. Stat. Comput. 8 483–500
Ascher U M, Christiansen J and Russell R D (1979) A collocation solver for mixed order systems of boundary value problems Math. Comput. 33 659–679
Ascher U M, Mattheij R M M and Russell R D (1988) Numerical Solution of Boundary Value Problems for Ordinary Differential Equations Prentice–Hall
Keller H B (1992) Numerical Methods for Two-point Boundary-value Problems Dover, New York
5 Arguments
- 1:
– function, supplied by the userExternal Function
-
ffun must evaluate the functions
for given values
.
The specification of
ffun is:
void |
ffun (double x,
const double y[],
Integer neq,
const Integer m[],
double f[],
Nag_Comm *comm)
|
|
- 1:
– doubleInput
-
On entry: , the independent variable.
- 2:
– const doubleInput
Note: the dimension,
dim, of the array
y
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 3:
– IntegerInput
-
On entry: the number of differential equations.
- 4:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 5:
– doubleOutput
-
On exit: must contain , for .
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
ffun.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
ffun when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 2:
– function, supplied by the userExternal Function
-
fjac must evaluate the partial derivatives of
with respect to the elements of
.
The specification of
fjac is:
void |
fjac (double x,
const double y[],
Integer neq,
const Integer m[],
double dfdy[],
Nag_Comm *comm)
|
|
- 1:
– doubleInput
-
On entry: , the independent variable.
- 2:
– const doubleInput
Note: the dimension,
dim, of the array
y
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 3:
– IntegerInput
-
On entry: the number of differential equations.
- 4:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 5:
– doubleInput/Output
Note: the dimension,
dim, of the array
dfdy
is
.
Where appears in this document, it refers to the array element .
On entry: set to zero.
On exit: must contain the partial derivative of with respect to , for , and . Only nonzero partial derivatives need be set.
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
fjac.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
fjac when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 3:
– function, supplied by the userExternal Function
-
gafun must evaluate the boundary conditions at the left-hand end of the range, that is functions
for given values of
.
The specification of
gafun is:
void |
gafun (const double ya[],
Integer neq,
const Integer m[],
Integer nlbc,
double ga[],
Nag_Comm *comm)
|
|
- 1:
– const doubleInput
Note: the dimension,
dim, of the array
ya
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 2:
– IntegerInput
-
On entry: the number of differential equations.
- 3:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 4:
– IntegerInput
-
On entry: the number of boundary conditions at .
- 5:
– doubleOutput
-
On exit: must contain , for .
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
gafun.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
gafun when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 4:
– function, supplied by the userExternal Function
-
gbfun must evaluate the boundary conditions at the right-hand end of the range, that is functions
for given values of
.
The specification of
gbfun is:
void |
gbfun (const double yb[],
Integer neq,
const Integer m[],
Integer nrbc,
double gb[],
Nag_Comm *comm)
|
|
- 1:
– const doubleInput
Note: the dimension,
dim, of the array
yb
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 2:
– IntegerInput
-
On entry: the number of differential equations.
- 3:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 4:
– IntegerInput
-
On entry: the number of boundary conditions at .
- 5:
– doubleOutput
-
On exit: must contain , for .
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
gbfun.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
gbfun when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 5:
– function, supplied by the userExternal Function
-
gajac must evaluate the partial derivatives of
with respect to the elements of
.
The specification of
gajac is:
void |
gajac (const double ya[],
Integer neq,
const Integer m[],
Integer nlbc,
double dgady[],
Nag_Comm *comm)
|
|
- 1:
– const doubleInput
Note: the dimension,
dim, of the array
ya
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 2:
– IntegerInput
-
On entry: the number of differential equations.
- 3:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 4:
– IntegerInput
-
On entry: the number of boundary conditions at .
- 5:
– doubleInput/Output
Note: the dimension,
dim, of the array
dgady
is
.
Where appears in this document, it refers to the array element .
On entry: set to zero.
On exit: must contain the partial derivative of with respect to , for , and . Only nonzero partial derivatives need be set.
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
gajac.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
gajac when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 6:
– function, supplied by the userExternal Function
-
gbjac must evaluate the partial derivatives of
with respect to the elements of
.
The specification of
gbjac is:
void |
gbjac (const double yb[],
Integer neq,
const Integer m[],
Integer nrbc,
double dgbdy[],
Nag_Comm *comm)
|
|
- 1:
– const doubleInput
Note: the dimension,
dim, of the array
yb
is
.
Where appears in this document, it refers to the array element
.
On entry: contains , for and .
Note: .
- 2:
– IntegerInput
-
On entry: the number of differential equations.
- 3:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 4:
– IntegerInput
-
On entry: the number of boundary conditions at .
- 5:
– doubleInput/Output
Note: the dimension,
dim, of the array
dgbdy
is
.
Where appears in this document, it refers to the array element .
On entry: set to zero.
On exit: must contain the partial derivative of with respect to , for , and . Only nonzero partial derivatives need be set.
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
gbjac.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
gbjac when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 7:
– function, supplied by the userExternal Function
-
guess must return initial approximations for the solution components
and the derivatives
, for
and
. Try to compute each derivative
such that it corresponds to your approximations to
, for
. You should
not call
ffun to compute
.
If nag_ode_bvp_coll_nlin_solve (d02tlc) is being used in conjunction with
nag_ode_bvp_coll_nlin_contin (d02txc) as part of a continuation process, then
guess is not called by nag_ode_bvp_coll_nlin_solve (d02tlc) after the call to
nag_ode_bvp_coll_nlin_contin (d02txc).
The specification of
guess is:
void |
guess (double x,
Integer neq,
const Integer m[],
double y[],
double dym[],
Nag_Comm *comm)
|
|
- 1:
– doubleInput
-
On entry: , the independent variable; .
- 2:
– IntegerInput
-
On entry: the number of differential equations.
- 3:
– const IntegerInput
-
On entry:
contains , the order of the th differential equation, for .
- 4:
– doubleOutput
Note: the dimension,
dim, of the array
y
is
.
Where appears in this document, it refers to the array element
.
On exit: must contain , for and .
Note: .
- 5:
– doubleOutput
-
On exit: must contain , for .
- 6:
– Nag_Comm *
Pointer to structure of type Nag_Comm; the following members are relevant to
guess.
- user – double *
- iuser – Integer *
- p – Pointer
The type Pointer will be
void *. Before calling nag_ode_bvp_coll_nlin_solve (d02tlc) you may allocate memory and initialize these pointers with various quantities for use by
guess when called from nag_ode_bvp_coll_nlin_solve (d02tlc) (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 8:
– doubleCommunication Array
-
Note: the dimension,
, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument
rcomm in the previous call to
nag_ode_bvp_coll_nlin_setup (d02tvc).
On entry: this must be the same array as supplied to
nag_ode_bvp_coll_nlin_setup (d02tvc) and
must remain unchanged between calls.
On exit: contains information about the solution for use on subsequent calls to associated functions.
- 9:
– IntegerCommunication Array
-
Note: the dimension,
, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument
icomm in the previous call to
nag_ode_bvp_coll_nlin_setup (d02tvc).
On entry: this must be the same array as supplied to
nag_ode_bvp_coll_nlin_setup (d02tvc) and
must remain unchanged between calls.
On exit: contains information about the solution for use on subsequent calls to associated functions.
- 10:
– Nag_Comm *
-
The NAG communication argument (see
Section 2.3.1.1 in How to Use the NAG Library and its Documentation).
- 11:
– NagError *Input/Output
-
The NAG error argument (see
Section 2.7 in How to Use the NAG Library and its Documentation).
6 Error Indicators and Warnings
- NE_ALLOC_FAIL
-
Dynamic memory allocation failed.
See
Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.
- NE_BAD_PARAM
-
On entry, argument had an illegal value.
- NE_CONVERGENCE_SOL
-
All Newton iterations that have been attempted have failed to converge.
No results have been generated. Check the coding of the functions for calculating the Jacobians of system and boundary conditions.
Try to provide a better initial solution approximation.
- NE_INTERNAL_ERROR
-
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact
NAG for assistance.
An unexpected error has been triggered by this function. Please contact
NAG.
See
Section 2.7.6 in How to Use the NAG Library and its Documentation for further information.
- NE_MISSING_CALL
-
Either the setup function has not been called or the communication arrays have become corrupted. No solution will be computed.
- NE_NO_LICENCE
-
Your licence key may have expired or may not have been installed correctly.
See
Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.
- NE_SING_JAC
-
Numerical singularity has been detected in the Jacobian used in the Newton iteration.
No results have been generated. Check the coding of the functions for calculating the Jacobians of system and boundary conditions.
- NW_MAX_SUBINT
-
The expected number of sub-intervals required to continue the computation exceeds the maximum specified: .
Results have been generated which may be useful.
Try increasing this number or relaxing the error requirements.
- NW_NOT_CONVERGED
-
A Newton iteration has failed to converge. The computation has not succeeded but results have been returned for an intermediate mesh on which convergence was achieved.
These results should be treated with extreme caution.
7 Accuracy
The accuracy of the solution is determined by the argument
tols in the prior call to
nag_ode_bvp_coll_nlin_setup (d02tvc) (see
Sections 3 and
9 in nag_ode_bvp_coll_nlin_setup (d02tvc) for details and advice). Note that error control is applied only to solution components (variables) and not to any derivatives of the solution. An estimate of the maximum error in the computed solution is available by calling
nag_ode_bvp_coll_nlin_diag (d02tzc).
8 Parallelism and Performance
nag_ode_bvp_coll_nlin_solve (d02tlc) is threaded by NAG for parallel execution in multithreaded implementations of the NAG Library.
nag_ode_bvp_coll_nlin_solve (d02tlc) makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.
Please consult the
x06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the
Users' Note for your implementation for any additional implementation-specific information.
If nag_ode_bvp_coll_nlin_solve (d02tlc) returns with
NE_CONVERGENCE_SOL,
NE_SING_JAC,
NW_MAX_SUBINT or
NW_NOT_CONVERGED and the call to nag_ode_bvp_coll_nlin_solve (d02tlc) was a part of some continuation procedure for which successful calls to nag_ode_bvp_coll_nlin_solve (d02tlc) have already been made, then it is possible that the adjustment(s) to the continuation parameter(s) between calls to nag_ode_bvp_coll_nlin_solve (d02tlc) is (are) too large for the problem under consideration. More conservative adjustment(s) to the continuation parameter(s) might be appropriate.
10 Example
The following example is used to illustrate the treatment of a high-order system, control of the error in a derivative of a component of the original system, and the use of continuation. See also
nag_ode_bvp_coll_nlin_setup (d02tvc),
nag_ode_bvp_coll_nlin_contin (d02txc),
nag_ode_bvp_coll_nlin_interp (d02tyc) and
nag_ode_bvp_coll_nlin_diag (d02tzc), for the illustration of other facilities.
Consider the steady flow of an incompressible viscous fluid between two infinite coaxial rotating discs. See
Ascher et al. (1979) and the references therein. The governing equations are
subject to the boundary conditions
where
is the Reynolds number and
are the angular velocities of the disks.
We consider the case of counter-rotation and a symmetric solution, that is
. This problem is more difficult to solve, the larger the value of
. For illustration, we use simple continuation to compute the solution for three different values of
(
). However, this problem can be addressed directly for the largest value of
considered here. Instead of the values suggested in
Section 5 in nag_ode_bvp_coll_nlin_contin (d02txc) for
nmesh,
ipmesh and
mesh in the call to
nag_ode_bvp_coll_nlin_contin (d02txc) prior to a continuation call, we use every point of the final mesh for the solution of the first value of
, that is we must modify the contents of
ipmesh. For illustrative purposes we wish to control the computed error in
and so recast the equations as
subject to the boundary conditions
For the symmetric boundary conditions considered, there exists an odd solution about
. Hence, to satisfy the boundary conditions, we use the following initial approximations to the solution in
guess:
10.1 Program Text
Program Text (d02tlce.c)
10.2 Program Data
Program Data (d02tlce.d)
10.3 Program Results
Program Results (d02tlce.r)