Last available version 1.2 (October 2011).

• Version 1.3: in development phase
  
  
• Version 1.2: October 2011
  1. M1CG1 is now distributed under the QPL License.
  2. Stopping criterion on the relative or absolute residual.
  3. Possibility to build an l-BFGS preconditioner from a previously constructed one (this was already possible for a BFGS preconditionner).
  4. Restructuring the solver directory. In particular, examples have been added in the directory examples.
  5. The documentation has been significantly improved. It gives the results testing the abilities of the solver.
  6. Cosmetic improvements.
  
  
• Version 1.1c: August 1999
  1. epsneg(O) gives the last Rayleigh quotient encountered,
  2. imode(3)=1 gives to epsneg another meaning.
  3. Careful control on the number of MV-products, with a flag allowing N1CG1 not to do the first MV-product when the first iterate is zero, as in truncated Newton algorithms. Hence, there are now the possibility of having two input modes (cf. imode(2)).
  4. N1cg1 is now able to solve two linear systems simultaneously using a single set of conjugate directions.
  
  
• Version 1.0: July 1998
  1. Initial version of N1CG1.