Free solver software for linux

pdnMesh is an automatic mesh generator and solver for Finite Element problems. It will also do post-processing to generate contour plots and Postscript printouts. GUI support using GTK or MFC (Win32) is available.

The problem definition can be done in any form and given to pdnMesh as an input data file. Drawing Exchange Format (DXF) files can be directly imported to pdnmesh. The quality and the coarseness of the mesh can be controlled by giving input parameters.

Java Sudoku is a cross platform version of the popular Sudoku logic game. Java Sudoku features an advanced user interface that is both easy to use and appealing to the eye.
It allows you to generate completely random Sudoku puzzles, enter your own puzzles from newspapers and magazines, or load them from Sudoku XML files. Java Sudoku can also be used as a Sudoku generator and solver.
Main features:
- Random puzzles every time you play
- Helping lines mode in the option menu, so You can see easier, if there is a collision
- 2 different systems of selecting cells and entering numbers
- 3 difficulty levels and an user custom level
- 3 Different Numbers Distributions
- Load/Save Sudoku games without any kind of losses
- Design your own puzzles - Under construction

LinAl was designed to bring together C++ and FORTRAN. At the same time LinAl is supposed to be easy to use, fast, and reasonably safe.

LinAl library is based on STL techniques and uses the STL containers for the storage of matrix data and STL algorithms where feasible.

Low level, algebraic operators, linear solvers, and eigenvalue solvers are implemented, based on calls to BLAS, LAPACK, and CGSOLX.

At the same time LinAl is supposed to be easy to use, fast and, to a certain extent, type save. While certain compromises were made in the class layout and design, strong emphasis was put on simplicity and speed.

The library is based on STL techniques and uses STL containers for the storage of matrix data furthermore STL algorithms are used where feasible. Low level, algebraic operators as well as linear solvers and eigenvalue solvers are implemented, based on calls to BLAS, LAPACK and CGSOLX and LANCZOS. These packages can be found on netlib.

Interested? Fantastic, download the package, get them compiler hummin and see whats this all about. Problems? Thats what the mailing list is for. So what are you waiting for?

A Sudoku Solver in C is a console-based Linux program, written in C language, that solves Su Doku puzzles using deductive logic. It will only resort to trial-and-error and backtracking approaches upon exhausting its deductive moves.
Puzzles must be of the standard 9x9 variety using the (ASCII) characters 1 through 9 for the puzzle symbols. Puzzles should be submitted as 81 character strings which, when read left-to-right will fill a 9x9 Sudoku grid from left-to-right and top-to-bottom. In the puzzle specification, the characters 1 - 9 represent the puzzle givens or clues. Any other non-blank character represents an unsolved cell.
The puzzle solving algorithm is home grown. I did not borrow any of the usual techniques from the literature, e.g. Donald Knuths "Dancing Links." Instead I rolled my own from scratch as a personal challenge. As such, its performance can only be blamed on yours truly. Still, I feel it is quite fast. On a 333 MHz Pentium II Linux box it solves typical medium force puzzles in approximately 800 microseconds or about 1,200 puzzles per second, give or take. On an Athlon XP 3000 it solves about 6,600 puzzles per sec. (Solving time is dependent upon degree of difficulty, so YMMV.)
Description of Algorithm:
The puzzle algorithm initially assumes every unsolved cell can assume every possible value. It then uses the placement of the givens to refine the choices available to each cell. I call this the markup phase.
After markup completes, the algorithm then looks for singleton cells with values that, due to constraints imposed by the row, column, or 3x3 region, may only assume one possible value. Once these cells are assigned values, the algorithm returns to the markup phase to apply these changes to the remaining candidate solutions. The markup/singleton phases alternate until either no more changes occur, or the puzzle is solved. I call the markup/singleton elimination loop the Simple Solver because in a large percentage of cases it solves the puzzle.
If the simple solver portion of the algorithm doesnt produce a solution, then more advanced deductive rules are applied.
Ive implemented two additional rules as part of the deductive puzzle solver. The first is subset elimination wherein a row/column/region is scanned for X number of cells with X number of matching candidate solutions. If such subsets (or tuples) are found in the row, column, or region, then the candidates values from the subset may be eliminated from all other unsolved cells within the row, column, or region, respectively.
The next deductive rule examines each region looking for candidate values that exclusively align themselves along a single row or column, i.e. a vector. If such candidate values are found, then they may be eliminated from the cells outside of the region that are part of the aligned row or column.
Note that each of the advanced deductive rules calls all preceeding rules, in order, if that advanced rule has effected a change in puzzle markup.
Finally, if no solution is found after iteratively applying all deductive rules, then we begin trial-and-error using recursion for backtracking. A working copy is created from our puzzle, and using this copy the first cell with the smallest number of candidate solutions is chosen. One of the solutions values is assigned to that cell, and the solver algorithm is called using this working copy as its starting point. Eventually, either a solution, or an impasse is reached.
If we reach an impasse, the recursion unwinds and the next trial solution is attempted. If a solution is found (at any point) the values for the solution are added to a list. Again, so long as we are examining all possibilities, the recursion unwinds so that the next trial may be attempted. It is in this manner that we enumerate puzzles with multiple solutions.
Note that it is certainly possible to add to the list of applied deductive rules. The techniques known as "X-Wing" and "Swordfish" come to mind. On the other hand, adding these additional rules will, in all likelihood, slow the solver down by adding to the computational burden while producing very few results. Ive seen the law of diminishing returns even in some of the existing rules, e.g. in subset elimination I only look at two and three valued subsets because taking it any further than that degraded performance.
Enhancements:
- Code optimization has resulted in a 30% increase in speed.

Template Numerical Toolkit (TNT) is a collection of interfaces and reference implementations of numerical objects useful for scientific computing in C++.
The toolkit defines interfaces for basic data structures, such as multidimensional arrays and sparse matrices, commonly used in numerical applications. Template Numerical Toolkits goal is to provide reusable software components that address many of the portability and maintennace problems with C++ codes.
TNT provides a distinction between interfaces and implementations of TNT components. For example, there is a TNT interface for two-dimensional arrays which describes how individual elements are accessed and how certain information, such as the array dimensions, can be used in algorithms; however, there can be several implementations of such an interface: one that uses expression templates, or one that uses BLAS kernels, or another that is instrumented to provide debugging information.
By specifying only the interface, applications codes may utilize such algorithms, while giving library developers the greatest flexibility in employing optimization or portability strategies.
TNT Data Structures
- C-style arrays
- Fortran-style arrays
- Sparse Matrices
- Vector/Matrix
TNT utilities
- array I/O
- math routines (hypot(), sign(), etc.)
- Stopwatch class for timing measurements
Libraries that utilize TNT
- JAMA: a linear algebra library with QR, SVD, Cholesky and Eigenvector solvers.
- old (pre 1.0) TNT routines for LU, QR, and Eigenvalue problems

OpenTaxSolver (OTS) project is a free program for calculating Tax Form entries and tax-owed or refund-due, such as Federal or State personal income taxes.
An optional graphical front-end, OTS_GUI, has been added. Currently, TaxSolver has been updated for the 2005 tax-year for the following forms: US 1040 and Schedules A, B, C, & D.
As well as for California, Massachusetts, New Jersey, and Pennsylvania State Taxes for 2005 tax-year, thanks to contributors. Updates for the following additional states are expected to be posted soon: North Carolina, New York, Ohio, and Virginia. Preliminary versions for Canada and the United Kingdom were posted in previous years and may be updated with help from volunteers.
Motivations:
- To make tax preparation software available for all platforms.
- To provide insight into how our taxes are calculated in clear unambiguous equations/code.
- To avoid invasive, bloated commercial software packages.
- To avoid rewriting our own individual programs each year by combining efforts.
- To provide a simple reliable tax-package requiring only rudimentary knowledge to maintain.
Enhancements:
- Automatic phone credit was added to US1040.
- It will automatically calculate standard one-time phone credit, if not otherwise specified on US1040 line 71.
- The NJ State form F line 5 was fixed.

Solving word problems is an area where elementary students overwhelmingly display difficulties. Master Math Word Problems program can help sharpen skills through practice. Third through fifth graders learn to watch for key words and translate those into mathematical operations.

Students can learn new math skills, practice logic, get extended practice with word problems, but most of all they learn that they must read the problem. With regular practice your students may become master math word problem solvers.

Download and try out Master Math Word Problems.