Merge remote-tracking branch 'origin/v10-minor'

Author: scip-ci

CHANGELOG

@@ -73,6 +73,7 @@ Fixed bugs
 - correct memory reallocation in storeSubproblemMasterVar() of benders.c to avoid freeing errors
 - also set real solution in SCIPsolSetValExact() to maintain approximation
 - handle exact solutions in SCIPsolCheckOrig(), SCIPcheckSolOrig(), and SCIPrecomputeSolObj() to correctly check exact initial solutions in SCIPtransformProb()
+- fixed use of interactive option (-i) of AMPL interface
 
 Miscellaneous
 -------------

doc/inc/faq/faqtext.txt

@@ -66,27 +66,18 @@ SECTION: General Questions about SCIP
     <p>Unless you want to use SCIP as a pure CP-Solver (see <a href="#scipascpsolver">here</a>),
       you need an underlying LP-Solver installed and linked to the libraries
       (see the <code><a href="PATHTODOC/INSTALL.LINKEXT">INSTALL</a></code> file in the SCIP root directory).
-      LP-solvers currently supported by SCIP are:
+      See <a href="PATHTODOC/LPI.LINKEXT">here</a> for LP-solvers currently supported by SCIP.
+      When solving MIPs exactly, an <a href="PATHTODOC/LPIEXACT.LINKEXT">exact LP solver supported by SCIP</a> is required.
     </p>
-    <ul>
-      <li><a href="https://soplex.zib.de/">SoPlex</a></li>
-      <li><a href="http://www-01.ibm.com/software/integration/optimization/cplex-optimizer/">IBM ILOG CPLEX</a></li>
-      <li><a href="http://www.fico.com/en/Products/DMTools/Pages/FICO-Xpress-Optimization-Suite.aspx">FICO XPress</a></li>
-      <li><a href="http://www.gurobi.com/">Gurobi</a> (version at least 7.0.2 required)</li>
-      <li><a href="https://projects.coin-or.org/Clp/">CLP</a> (interface currently sometimes produces wrong results)</li>
-      <li><a href="https://github.com/google/or-tools">Glop, Google OR tools</a> (experimental, LPI contained in OR tools)</li>
-      <li><a href="http://www.mosek.com/">Mosek</a></li>
-      <li><a href="http://www2.isye.gatech.edu/~wcook/qsopt/">QSopt</a> (experimental)</li>
-    </ul>
     <p>
-      If you want to use SCIP for mixed integer nonlinear programming, you might want to use an underlying NLP solver (e.g.,
-      <a href="https://projects.coin-or.org/Ipopt">Ipopt</a> or <a href="https://www.conopt.com">CONOPT</a>). SCIP already
-      comes with the CppAD expression interpreter (e.g., <a href="http://www.coin-or.org/CppAD/">CppAD</a>) as part of the source code.
+      If you want to use SCIP for mixed integer nonlinear programming, linking an <a href="PATHTODOC/NLPISOLVERS.LINKEXT">NLP solver supported by SCIP</a> is strongly advised.
+      The automatic differentiation library <a href="https://github.com/coin-or/CppAD">CppAD</a> is redistributed as part of the SCIP source code.
     </p>
     <p>
       Besides that, you might need a modeling language like <a href="https://zimpl.zib.de/">ZIMPL</a> to generate *.mps
       or *.lp files. ZIMPL files (.zpl extension) can also be read directly into SCIP.
-      Downloading the SCIP Optimization Suite includes SCIP, SoPlex and ZIMPL, as well as GCG and UG. Find installers for different platforms
+      Further, linking <a href="https://github.com/scipopt/papilo">PaPILO</a> can provide a stronger presolve when solving MIP.
+      Downloading the SCIP Optimization Suite includes SCIP, SoPlex and ZIMPL, as well as GCG, PaPILO, and UG. Find installers for different platforms
       and the source code bundle of all versions <a href="https://scipopt.org/#download">here</a>.
     </p>
 

doc/xternal.c

@@ -9197,14 +9197,33 @@
   * - <a href="https://zimpl.zib.de">ZIMPL</a>, a modeling language for constraint programming,
   * - both <a href="http://www.ampl.com/">AMPL</a> and <a href="http://www.gams.com">GAMS</a>,
   *   are well-suited for modeling mixed-integer linear and nonlinear optimization problems,
-  * - and <a href="https://projects.coin-or.org/Cmpl">CMPL</a> for mixed-integer linear problems.
+  * - and <a href="https://coliop.org/">CMPL</a> for mixed-integer linear problems.
   * - <a href="https://jump.dev/JuMP.jl/stable/">JuMP</a> accesses SCIP through the Julia interface.
   * - <a href="http://users.isy.liu.se/johanl/yalmip/pmwiki.php?n=Main.HomePage">YALMIP</a> by Johan L&ouml;fberg provides a
   *   free modeling language.
   *
   * The AMPL and ZIMPL interfaces are included in the \SCIP distribution,
   * the GAMS interface is available <a href="https://github.com/coin-or/GAMSlinks">here</a>.
   *
+  * @subsection AMPL AMPL Interface
+  *
+  * The AMPL interface is part of the main \SCIP executable.
+  * It is activated when the executable is called with the name of the AMPL `.nl` file as first argument and `-AMPL` as second argument.
+  * In this case, \SCIP will employ the \ref reader_nl.h "NL reader" to read the `.nl` file (and `.col`  and `.row` files with variable and constraint names, if available),
+  * read parameter settings from a `scip.set` file (if present), attempt to solve the problem, write an AMPL solution file with the solve output, and exit.
+  * However, if `-i` is given as third argument, then solving the problem is replaced by opening the \ref SHELL "interactive shell".
+  *
+  * Next to a `scip.set` file, parameter settings can also be given via an `option` command in AMPL, e.g.,
+  * ```
+  * option scip_options 'limits/gap = 1e-4 display/statistics = TRUE';
+  * ```
+  * Parameter `display/statistics` is specific to using \SCIP via the AMPL interface and triggers a call to \ref SCIPprintStatistics after the problem has been solved (or the interactive shell has been exited).
+  * In addition, a parameter `display/logfile` is available to specify a file to which to print \SCIP output in addition to stdout.
+  *
+  * For most problems, \SCIP computes a primal solution only.
+  * A dual solution is written to an AMPL solution file only if an LP has been solved with presolve disabled.
+  *
+  * \SCIP is also able to write AMPL `.nl` files (and `.col`  and `.row` files with variable and constraint names). See \ref reader_nl.h for currently supported constraint types.
   */
 
  /**@defgroup PUBLICAPI Public API of SCIP

src/scip/reader_nl.cpp

@@ -963,7 +963,7 @@ class AMPLProblemHandler : public mp::NLHandler<AMPLProblemHandler, SCIP_EXPR*>
 
    /// handling of suffices for variable and constraint flags and SOS constraints
    ///
-   /// regarding SOS in AMPL, see https://ampl.com/faqs/how-can-i-use-the-solvers-special-ordered-sets-feature/
+   /// regarding SOS in AMPL, see https://discuss.ampl.com/t/how-can-i-use-the-solver-s-special-ordered-sets-feature/45
    /// we pass the .ref suffix as weight to the SOS constraint handlers
    /// for a SOS2, the weights determine the order of variables in the set
    template<typename T> class SuffixHandler

src/scip/reader_nl.h

@@ -26,6 +26,29 @@
  * @ingroup FILEREADERS
  * @brief  AMPL .nl file reader and writer
  * @author Stefan Vigerske
+ *
+ * \par Reading Functionality
+ *
+ * The reader supports linear, nonlinear, and logic constraints, with the following limitations:
+ * - For nonlinear expressions, only unary operators minus (negation), abs, pow2, sqrt, log, log10, exp, sin, cos,
+ *   binary operators add, sub, mul, div, pow, and n-ary operator sum are supported.
+ * - For logical constraints, only operators not, or, and, iff, eq, and ne are supported and all arguments must
+ *   be either boolean values or binary variables! The reader currently does not support logical operations that
+ *   use algebraic or linear expressions, and therefore not the creation of indicator constraints.
+ *
+ * In addition, the reader creates special ordered set (SOS) constraints of type 1 and 2 if they were specified via
+ * [`sosnr` suffixes](https://discuss.ampl.com/t/how-can-i-use-the-solver-s-special-ordered-sets-feature/45).
+ * Values specified via `ref` suffix are passed on as weights to the SOS constraint handlers.
+ * For SOS of type 2, the weights determine the order of variables in the SOS.
+ *
+ * Next to SOS, suffixes can be used to specify flags of variables (see \ref SCIPcreateVar()) and constraints
+ * (see \ref SCIPcreateCons()). For variables, supported suffixes are `initial` and `removable`. For constraints,
+ * supported suffixes are `initial`, `separate`, `enforce`, `check`, `propagate`, `dynamic`, and `removable`.
+ *
+ * \par Writing Functionality
+ *
+ * The writer currently supports the constraint handlers linear, setppc, logicor, knapsack, varbound, and nonlinear only.
+ * When writing nonlinear constraints, expression handlers entropy and signpower are currently not supported.
  */
 
 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/

src/scip/scipshell.c

@@ -248,17 +248,23 @@ SCIP_RETCODE fromAmpl(
       (void) SCIPsnprintf(fullnlfilename, SCIP_MAXSTRLEN, "%s", nlfilename);
    else
       (void) SCIPsnprintf(fullnlfilename, SCIP_MAXSTRLEN, "%s.nl", nlfilename);
-   SCIPinfoMessage(scip, NULL, "read problem <%s>\n", fullnlfilename);
-   SCIPinfoMessage(scip, NULL, "============\n\n");
-
-   SCIP_CALL( SCIPreadProb(scip, fullnlfilename, "nl") );
 
    if( interactive )
    {
+      char readcommand[SCIP_MAXSTRLEN+6];
+
+      (void) SCIPsnprintf(readcommand, (int)sizeof(readcommand), "read %s", fullnlfilename);
+      SCIP_CALL( SCIPaddDialogInputLine(scip, readcommand) );
+
       SCIP_CALL( SCIPstartInteraction(scip) );
    }
    else
    {
+      SCIPinfoMessage(scip, NULL, "read problem <%s>\n", fullnlfilename);
+      SCIPinfoMessage(scip, NULL, "============\n\n");
+
+      SCIP_CALL( SCIPreadProb(scip, fullnlfilename, "nl") );
+
       SCIPinfoMessage(scip, NULL, "\nsolve problem\n");
       SCIPinfoMessage(scip, NULL, "=============\n\n");
 
@@ -274,7 +280,10 @@ SCIP_RETCODE fromAmpl(
       SCIP_CALL( SCIPprintStatistics(scip, NULL) );
    }
 
-   SCIP_CALL( SCIPwriteSolutionNl(scip) );
+   if( SCIPgetStage(scip) > SCIP_STAGE_PROBLEM )
+   {
+      SCIP_CALL( SCIPwriteSolutionNl(scip) );
+   }
 
    return SCIP_OKAY;