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Suggested Citation:"Translating TRIM2 Modules to the C Language." National Research Council. 1991. Improving Information for Social Policy Decisions -- The Uses of Microsimulation Modeling: Volume II, Technical Papers. Washington, DC: The National Academies Press. doi: 10.17226/1853.
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FUTURE COMPUTING ENVIRONMENTS FOR MICROSIMULATION MODELING 222 Significant work would be required to perform such a port. It would likely take 1 person-year of work, possibly more, by competent software engineers with experience in both MS-DOS and IBM MVS environments. The task is nontrivial; it includes not only code conversion but also conversion of the many procedures currently embodied in the IBM MVS JCL. Validation of the port at the model output level is a complex task important to ensuring that the algorithms in TRIM2, which account for much of its capital content, have been preserved. Porting TRIM2 to a UNIX Environme nt UNIX was originally developed for minicomputer systems and was later adopted for use in scientific workstations. The architectures of these hardware environments have typically been characterized by substantially more real memory and virtual address space than MS-DOS environments as well as by larger disk storage devices and the use of disk server systems linked by high-speed network connections.89 FORTRAN-language translators are available for UNIX-based desktop systems that are at least the equivalent of MS-DOS FORTRAN translators. COBOL-language processors are more scarce, and such a port might require rewriting the current code that manages the CTD, probably in the C language. Such a module could then be called from a FORTRAN subprogram, so that integration of directory functions with the rest of the system could be maintained. Porting TRIM2 to a UNIX environment would be somewhat easier than porting it to an MS-DOS environment, partly because of the more sophisticated and powerful software development environment and related tools available in typical UNIX environments. The port would still be somewhat lengthy and require software engineers with experience in UNIX and IBM MVS. Translating TRIM2 Modules to the C Language Discussion of these ports assumes that the TRIM2 code remains in FORTRAN and that the code would be changed as little as possible during the port. Any change has the potential of introducing problems in that every source of variance between old and new environments threatens the functional equivalence of the new version of the system with the old. Potential small differences in the language processors (compilers) should themselves be viewed with concern, 89 UNIX workstations are typically connected using Ethernet, which transmits at speeds of 10 MB/second nominal and 4 MB/second expected. Assuming that the network is uncongested and that expected speeds are attainable, the transfer rate for files over the network is comparable to the transfer rate of files from a fixed disk on an MS-DOS system. Thus, using capacious file server capability on a UNIX network may be an acceptable substitute for large amounts of local fixed disk capacity for certain applications.

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Improving Information for Social Policy Decisions -- The Uses of Microsimulation Modeling: Volume II, Technical Papers Get This Book
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This volume, second in the series, provides essential background material for policy analysts, researchers, statisticians, and others interested in the application of microsimulation techniques to develop estimates of the costs and population impacts of proposed changes in government policies ranging from welfare to retirement income to health care to taxes.

The material spans data inputs to models, design and computer implementation of models, validation of model outputs, and model documentation.

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