# naginterfaces.library.ode.dae_​dassl_​setup¶

naginterfaces.library.ode.dae_dassl_setup(neq, maxord, jceval, hmax, h0, itol)[source]

dae_dassl_setup is a setup function which must be called prior to the integrator dae_dassl_gen(), if the DASSL implementation of Backward Differentiation Formulae (BDF) is to be used.

For full information please refer to the NAG Library document for d02mw

https://www.nag.com/numeric/nl/nagdoc_29/flhtml/d02/d02mwf.html

Parameters
neqint

The number of differential-algebraic equations to be solved.

maxordint

The maximum order to be used for the BDF method. Orders up to 5th order are available; setting means that the maximum order used will be .

jcevalstr, length 1

Specifies the technique to be used to compute the Jacobian.

The Jacobian is to be evaluated numerically by the integrator.

You must supply a function to evaluate the Jacobian on a call to the integrator.

Only the first character of the actual paramater is passed to dae_dassl_setup; hence it is permissible for the actual argument to be more descriptive, e.g., ‘Numerical’ or ‘Analytical’, on a call to dae_dassl_setup.

hmaxfloat

The maximum absolute step size to be allowed. Set if this option is not required.

h0float

The step size to be attempted on the first step. Set if the initial step size is calculated internally.

itolint

A value to indicate the form of the local error test.

and are single element vectors.

and are vectors. This should be chosen if you want to apply different tolerances to each equation in the system.

Note: the tolerances must either both be single element vectors or both be vectors of length .

Returns
commdict, communication object

Communication structure.

Raises
NagValueError
(errno )

On entry, .

Constraint: .

(errno )

On entry, .

Constraint: .

(errno )

On entry, has an illegal value: .

Constraint: or .

(errno )

On entry, .

Constraint: .

(errno )

On entry, .

Constraint: or .

Notes

This integrator setup function must be called before the first call to the integrator dae_dassl_gen(). This setup function dae_dassl_setup permits you to define options for the DASSL integrator, such as: whether the Jacobian is to be provided or is to be approximated numerically by the integrator; the initial and maximum step-sizes for the integration; whether relative and absolute tolerances are system wide or per system equation; and the maximum order of BDF method permitted.