| Last Modified On : | August 28, 2009 5:12 PM PDT |
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Introduction
The interface to the PARDISO solver has many parameters and learning to use it for the first time can take a lot of time. The DSS interface for PARDISO was created to provide a simpler interface to the functionality, but often users still want to use the PARDISO interface. This article provides some tips for getting started and corrects some of the mistakes made by first-time users and even occasionally by experienced users.
General tips
Explore the examples in the examples/solver directory of MKL. By choosing an example program that solves a problem that is close to the sort of problem you will be solving you can get to know some of the most helpful and relevant parameter settings for your case.
Use the matrix checker: The iparm(27) parameter of PARDISO controls the input checker. By default it is turned off (iparm(27)=0), so you'll need to turn it on by setting iparm(27)=1. PARDISO will run some checks on your data structure and return an error message if it finds that something was wrong. This can help you find simple errors in your indexing as well as correct misunderstandings about how PARDISO expects your matrix to be represented and stored (e.g., a symmetric matrix should be stored in upper triangular form).
Check your link line:Sometimes a program linked against Intel MKL can misbehave (crash, hang, etc.) because the program was linked against the wrong threading layer (which assumes a specific threading runtime) or wrong interface (e.g., ILP64 v. LP64; cdecl v. stdcall). The link line advisor may be helpful if you're using the latest version of Intel MKL. For earlier versions you should consult the Intel MKL User's Guide chapter 5 on linking your application.
Important settings
Use message level information: The solver prints statistical information to the screen if the input parameter msglvl = 1 and generates no output if msglvl = 0. There is no default value for this option.
Single and double precision: Starting version 10.2 Intel® Math Kernel Library supports computations in single precision as well as double precision. To switch between single and double precision modes you should use iparm(28). The default mode of iparm(28) is 0, which corresponds to the double precision. If iparm(28) = 1 all internal computations are made in single precision. Please refer to this article for more information on these options.
Use default values: To get started quickly with PARDISO you can use the default values for each of the elements in the iparm array. Setting iparm(1) = 0 will cause PARDISO to use the default values for the rest of the array: iparm(2) and iparm(4) through iparm(64). Otherwise, you must supply all the values in the iparm array.
Rewrite the solution: if you need to store the output solution on the right hand side of array b, choose iparm(6) = 1.
The default value of iparm(6)=0, which corresponds array x contains the solution.
Other sources of information
If you're still having trouble and/or you suspect you've found a problem in Intel MKL, you might check the known issues article in the Intel MKL knowledgebase. Another option is to search the Intel MKL forum for other reports of a similar problem or post a question of your own.
The interface to the PARDISO solver has many parameters and learning to use it for the first time can take a lot of time. The DSS interface for PARDISO was created to provide a simpler interface to the functionality, but often users still want to use the PARDISO interface. This article provides some tips for getting started and corrects some of the mistakes made by first-time users and even occasionally by experienced users.
General tips
Explore the examples in the examples/solver directory of MKL. By choosing an example program that solves a problem that is close to the sort of problem you will be solving you can get to know some of the most helpful and relevant parameter settings for your case.
Use the matrix checker: The iparm(27) parameter of PARDISO controls the input checker. By default it is turned off (iparm(27)=0), so you'll need to turn it on by setting iparm(27)=1. PARDISO will run some checks on your data structure and return an error message if it finds that something was wrong. This can help you find simple errors in your indexing as well as correct misunderstandings about how PARDISO expects your matrix to be represented and stored (e.g., a symmetric matrix should be stored in upper triangular form).
Check your link line:Sometimes a program linked against Intel MKL can misbehave (crash, hang, etc.) because the program was linked against the wrong threading layer (which assumes a specific threading runtime) or wrong interface (e.g., ILP64 v. LP64; cdecl v. stdcall). The link line advisor may be helpful if you're using the latest version of Intel MKL. For earlier versions you should consult the Intel MKL User's Guide chapter 5 on linking your application.
Important settings
Use message level information: The solver prints statistical information to the screen if the input parameter msglvl = 1 and generates no output if msglvl = 0. There is no default value for this option.
Single and double precision: Starting version 10.2 Intel® Math Kernel Library supports computations in single precision as well as double precision. To switch between single and double precision modes you should use iparm(28). The default mode of iparm(28) is 0, which corresponds to the double precision. If iparm(28) = 1 all internal computations are made in single precision. Please refer to this article for more information on these options.
Use default values: To get started quickly with PARDISO you can use the default values for each of the elements in the iparm array. Setting iparm(1) = 0 will cause PARDISO to use the default values for the rest of the array: iparm(2) and iparm(4) through iparm(64). Otherwise, you must supply all the values in the iparm array.
Rewrite the solution: if you need to store the output solution on the right hand side of array b, choose iparm(6) = 1.
The default value of iparm(6)=0, which corresponds array x contains the solution.
Other sources of information
If you're still having trouble and/or you suspect you've found a problem in Intel MKL, you might check the known issues article in the Intel MKL knowledgebase. Another option is to search the Intel MKL forum for other reports of a similar problem or post a question of your own.
This article applies to: Intel® Fortran Compiler for Linux* Knowledge Base, Intel® Fortran Compiler for Mac OS X* Knowledge Base, Intel® Math Kernel Library Knowledge Base, Intel® Visual Fortran Compiler for Windows* Knowledge Base
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Author
Gennady Fedorov (Intel)
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Todd Rosenquist (Intel)
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