LSODE - Revision history

Jpye at 02:06, 28 September 2014

2014-09-28T02:06:17Z

← Older revision		Revision as of 02:06, 28 September 2014
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	This is the ASCEND binding to the well-known [http://www.llnl.gov/casc/odepack/download/lsode_agree.html '''LSODE''' solver from LLNL]. Provides multi-step ODE integration techniques both implicit and explicit (BDF and AM).		This is the ASCEND binding to the well-known [http://www.llnl.gov/casc/odepack/download/lsode_agree.html '''LSODE''' solver from LLNL]. Provides multi-step ODE integration techniques both implicit and explicit (BDF and AM).


	Note that although '''LSODE''' is an [[ODE]] solver, it is used in ASCEND as a [[DAE]] solver through the use of an 'inner loop' solver inside '''LSODE'''. The architecture at this stage is a bit messy: '''LSODE''' just wraps around the Solver instance of [[QRSlv]] currently assigned to the model (Simulation::setSolver). This needs to be generalised so that any [[NLA]] solver can be used for the inner loop.		Note that although '''LSODE''' is an [[ODE]] solver, it is used in ASCEND as a [[DAE]] solver through the use of an 'inner loop' solver inside '''LSODE'''. The architecture at this stage is a bit messy: '''LSODE''' just wraps around the Solver instance of [[QRSlv]] currently assigned to the model (Simulation::setSolver). This needs to be generalised so that any [[NLA]] solver can be used for the inner loop.


	'''LSODE''' extracts solutions for the differential variables using the [[QRSlv]] solution of from the inner loop (by FIXing the states and FREEing the derivatives). Then these derivatives and the corresponding differential variable are given to '''LSODE''' for time-stepping.		'''LSODE''' extracts solutions for the differential variables using the [[QRSlv]] solution of from the inner loop (by FIXing the states and FREEing the derivatives). Then these derivatives and the corresponding differential variable are given to '''LSODE''' for time-stepping.
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	This matrix is accessible using the integrator_write_matrix or Integrator::writeMatrix function and is written in a form that can be read into the Python <tt>scipy</tt> tool, Matlab, and elsewhere (the [[MatrixMarket]] format).		This matrix is accessible using the integrator_write_matrix or Integrator::writeMatrix function and is written in a form that can be read into the Python <tt>scipy</tt> tool, Matlab, and elsewhere (the [[MatrixMarket]] format).


	== Solver parameters ==		== Solver parameters ==
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	atol		atol
	</pre>		</pre>



	~~[[Category:Solvers]]~~
	~~[[Category:Stubs]]~~

Jpye at 10:14, 19 May 2010

2010-05-19T10:14:04Z

← Older revision		Revision as of 10:14, 19 May 2010
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	{{solvers}}		{{solvers}}
	{{~~missing~~}}		{{stub}}

			This is the ASCEND binding to the well-known [http://www.llnl.gov/casc/odepack/download/lsode_agree.html '''LSODE''' solver from LLNL]. Provides multi-step ODE integration techniques both implicit and explicit (BDF and AM).


			Note that although '''LSODE''' is an [[ODE]] solver, it is used in ASCEND as a [[DAE]] solver through the use of an 'inner loop' solver inside '''LSODE'''. The architecture at this stage is a bit messy: '''LSODE''' just wraps around the Solver instance of [[QRSlv]] currently assigned to the model (Simulation::setSolver). This needs to be generalised so that any [[NLA]] solver can be used for the inner loop.


			'''LSODE''' extracts solutions for the differential variables using the [[QRSlv]] solution of from the inner loop (by FIXing the states and FREEing the derivatives). Then these derivatives and the corresponding differential variable are given to '''LSODE''' for time-stepping.

			The use of an inner loop will make '''LSODE''' slower that [[IDA]] but it does have the benefit of giving a jacobian matrix from which system eigenvalues can be computed:

			<math>
			\frac{\partial x'}{\partial x}
			</math>

			This matrix is accessible using the integrator_write_matrix or Integrator::writeMatrix function and is written in a form that can be read into the Python <tt>scipy</tt> tool, Matlab, and elsewhere (the [[MatrixMarket]] format).


			== Solver parameters ==
			<pre>meth
			miter
			maxord
			timing
			rtolvect
			rtol
			atolvect
			atol
			</pre>



			[[Category:Solvers]]
			[[Category:Stubs]]

WikiSysop: Created page with '{{solvers}} {{missing}}'

2010-05-14T03:59:25Z

Created page with '{{solvers}} {{missing}}'

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