A singular system.

The following system is singular; apparently the solution is , but your decomposition routine should signal singularity by encountering very small pivots.

    0.1934    0.1509    0.8537    0.8216        2.0196
A=  0.6822    0.6979    0.5936    0.6449    b=  2.6186
    0.8756    0.8488    1.4473    1.4665        4.6382
    0.2481    0.2646    0.6752    0.8198        2.0077

The main program and all additional routines for this example will be submitted in a file lin_singular.f90.