support div in formulas (#188)

ckrause · web-flow · commit d418a72d9364 · 2022-10-16T19:10:20.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,10 @@ To install or update LODA, please follow the [installation instructions](https:/
 
 * Fix programs update interval
 
+### Enhancements
+
+* Support `div` in formulas
+
 # v22.10.14
 
 ### Enhancements
diff --git a/README.md b/README.md
@@ -51,7 +51,7 @@ Options:
   -t <number>         Number of sequence terms (default: 10)
   -b                  Print result in b-file format from offset 0
   -B <number>         Print result in b-file format from a custom offset
-  -o <string>         Export format (pari,loda)
+  -o <string>         Export format (formula,loda,pari)
   -s                  Evaluate program to number of execution steps
   -c <number>         Maximum number of interpreter cycles (no limit: -1)
   -m <number>         Maximum number of used memory cells (no limit: -1)
diff --git a/src/commands.cpp b/src/commands.cpp
@@ -82,7 +82,8 @@ void Commands::help() {
   std::cout << "  -B <number>         Print result in b-file format from a "
                "custom offset"
             << std::endl;
-  std::cout << "  -o <string>         Export format (pari,loda)" << std::endl;
+  std::cout << "  -o <string>         Export format (formula,loda,pari)"
+            << std::endl;
   std::cout << "  -s                  Evaluate program to number of "
                "execution steps"
             << std::endl;
@@ -190,12 +191,18 @@ void Commands::export_(const std::string& path) {
   Parser parser;
   Program program = parser.parse(getProgramPathAndSeqId(path).first);
   const auto& format = settings.export_format;
-  if (format.empty() || format == "pari") {
-    auto formula = Formula::fromProgram(program);
+  if (format.empty() || format == "formula") {
+    auto formula = Formula::fromProgram(program, false);
     if (!formula.first) {
       throw std::runtime_error("program cannot be converted to formula");
     }
     std::cout << Pari::generate(formula.second) << std::endl;
+  } else if (format == "pari") {
+    auto formula = Formula::fromProgram(program, true);
+    if (!formula.first) {
+      throw std::runtime_error("program cannot be converted to pari");
+    }
+    std::cout << Pari::generate(formula.second) << std::endl;
   } else if (format == "loda") {
     ProgramUtil::print(program, std::cout);
   } else {
@@ -302,7 +309,7 @@ void Commands::testPari() {
     }
     auto seq = manager.getSequences().at(id);
     auto program = parser.parse(seq.getProgramPath());
-    auto formula = Formula::fromProgram(program);
+    auto formula = Formula::fromProgram(program, true);
     if (!formula.first) {
       continue;
     }
diff --git a/src/formula.cpp b/src/formula.cpp
@@ -41,7 +41,7 @@ Expression operandToExpression(Operand op) {
   throw std::runtime_error("internal error");  // unreachable
 }
 
-std::pair<bool, Formula> Formula::fromProgram(const Program& p) {
+std::pair<bool, Formula> Formula::fromProgram(const Program& p, bool pariMode) {
   std::pair<bool, Formula> result;
   result.first = false;
   Formula& f = result.second;
@@ -66,7 +66,7 @@ std::pair<bool, Formula> Formula::fromProgram(const Program& p) {
 
   // update expressions using operations
   for (auto& op : p.ops) {
-    if (!f.update(op)) {
+    if (!f.update(op, pariMode)) {
       return result;  // operation not supported
     }
     Log::get().debug("Operation " + ProgramUtil::operationToString(op) +
@@ -113,7 +113,7 @@ Expression treeExpr(Expression::Type t, const Expression& c1,
   return result;
 }
 
-bool Formula::update(const Operation& op) {
+bool Formula::update(const Operation& op, bool pariMode) {
   auto source = operandToExpression(op.source);
   auto target = operandToExpression(op.target);
 
@@ -139,12 +139,26 @@ bool Formula::update(const Operation& op) {
       entries[target] =
           treeExpr(Expression::Type::PRODUCT, prevTargetValue, source);
       return true;
+    case Operation::Type::DIV:
+      if (pariMode) {
+        entries[target] = Expression(Expression::Type::FUNCTION, "truncate");
+        entries[target].newChild(
+            treeExpr(Expression::Type::FRACTION, prevTargetValue, source));
+
+      } else {
+        entries[target] =
+            treeExpr(Expression::Type::FRACTION, prevTargetValue, source);
+      }
+      return true;
     case Operation::Type::POW: {
-      if (CanBeNegative(source)) {
-        return false;
+      if (pariMode && CanBeNegative(source)) {
+        entries[target] = Expression(Expression::Type::FUNCTION, "truncate");
+        entries[target].newChild(
+            treeExpr(Expression::Type::POWER, prevTargetValue, source));
+      } else {
+        entries[target] =
+            treeExpr(Expression::Type::POWER, prevTargetValue, source);
       }
-      entries[target] =
-          treeExpr(Expression::Type::POWER, prevTargetValue, source);
       return true;
     }
     default:
diff --git a/src/include/formula.hpp b/src/include/formula.hpp
@@ -7,14 +7,14 @@
 
 class Formula {
  public:
-  static std::pair<bool, Formula> fromProgram(const Program& p);
+  static std::pair<bool, Formula> fromProgram(const Program& p, bool pariMode);
 
   std::string toString() const;
 
  private:
   std::map<Expression, Expression> entries;
 
-  bool update(const Operation& op);
+  bool update(const Operation& op, bool pariMode);
 
   void replaceAll(const Expression& from, const Expression& to);
 };
diff --git a/src/oeis_manager.cpp b/src/oeis_manager.cpp
@@ -645,9 +645,9 @@ void OeisManager::dumpProgram(size_t id, Program &p, const std::string &file,
     }
   }
   tmp.ops.push_back(nop);
-  auto formula = Formula::fromProgram(p);
+  auto formula = Formula::fromProgram(p, false);
   if (formula.first) {
-    nop.comment = formula.second.toString();
+    nop.comment = "Formula: " + formula.second.toString();
     tmp.ops.push_back(nop);
   }
   nop.comment.clear();
@@ -665,7 +665,7 @@ void OeisManager::alert(Program p, size_t id, const std::string &prefix,
   std::stringstream buf;
   buf << prefix << " program for " << seq
       << " Terms: " << seq.getTerms(settings.num_terms);
-  auto formula = Formula::fromProgram(p);
+  auto formula = Formula::fromProgram(p, false);
   if (formula.first) {
     buf << ". Formula: " << formula.second.toString();
   }
diff --git a/src/test.cpp b/src/test.cpp
@@ -887,7 +887,7 @@ void Test::formula() {
     OeisSequence seq(e.first);
     Log::get().info("Testing formula for " + seq.id_str() + ": " + e.second);
     auto p = parser.parse(seq.getProgramPath());
-    auto r = Formula::fromProgram(p);
+    auto r = Formula::fromProgram(p, false);
     if (!r.first) {
       Log::get().error("Cannot generate formula from program", true);
     }
diff --git a/tests/formula/program-formula.txt b/tests/formula/program-formula.txt
@@ -11,6 +11,7 @@ A001478: a(n)=-n-1
 A002489: a(n)=n^(n^2)
 A005408: a(n)=2*n+1
 A005843: a(n)=2*n
+A007583: a(n)=2*((4^n)/3)+1
 A008785: a(n)=(n+4)^n
 A022958: a(n)=2-n
 A318791: a(n)=(3*n-38)*(3*n-39)+41
diff --git a/tests/programs/oeis/007/A007583.asm b/tests/programs/oeis/007/A007583.asm
@@ -0,0 +1,9 @@
+; A007583: a(n) = (2^(2*n + 1) + 1)/3.
+; 1,3,11,43,171,683,2731,10923,43691,174763,699051,2796203,11184811,44739243,178956971,715827883,2863311531,11453246123,45812984491,183251937963,733007751851,2932031007403,11728124029611,46912496118443,187649984473771,750599937895083,3002399751580331,12009599006321323,48038396025285291,192153584101141163,768614336404564651,3074457345618258603,12297829382473034411,49191317529892137643,196765270119568550571,787061080478274202283,3148244321913096809131,12592977287652387236523,50371909150609548946091
+
+mov $1,4
+pow $1,$0
+div $1,3
+mul $1,2
+add $1,1
+mov $0,$1

Original file line number	Diff line number	Diff line change
`@@ -645,9 +645,9 @@ void OeisManager::dumpProgram(size_t id, Program &p, const std::string &file,`
`645`	`645`	`}`
`646`	`646`	`}`
`647`	`647`	`tmp.ops.push_back(nop);`
`648`		`- auto formula = Formula::fromProgram(p);`
	`648`	`+ auto formula = Formula::fromProgram(p, false);`
`649`	`649`	`if (formula.first) {`
`650`		`- nop.comment = formula.second.toString();`
	`650`	`+ nop.comment = "Formula: " + formula.second.toString();`
`651`	`651`	`tmp.ops.push_back(nop);`
`652`	`652`	`}`
`653`	`653`	`nop.comment.clear();`
`@@ -665,7 +665,7 @@ void OeisManager::alert(Program p, size_t id, const std::string &prefix,`
`665`	`665`	`std::stringstream buf;`
`666`	`666`	`buf << prefix << " program for " << seq`
`667`	`667`	`<< " Terms: " << seq.getTerms(settings.num_terms);`
`668`		`- auto formula = Formula::fromProgram(p);`
	`668`	`+ auto formula = Formula::fromProgram(p, false);`
`669`	`669`	`if (formula.first) {`
`670`	`670`	`buf << ". Formula: " << formula.second.toString();`
`671`	`671`	`}`
Original file line number	Diff line number	Diff line change
`@@ -887,7 +887,7 @@ void Test::formula() {`
`887`	`887`	`OeisSequence seq(e.first);`
`888`	`888`	`Log::get().info("Testing formula for " + seq.id_str() + ": " + e.second);`
`889`	`889`	`auto p = parser.parse(seq.getProgramPath());`
`890`		`- auto r = Formula::fromProgram(p);`
	`890`	`+ auto r = Formula::fromProgram(p, false);`
`891`	`891`	`if (!r.first) {`
`892`	`892`	`Log::get().error("Cannot generate formula from program", true);`
`893`	`893`	`}`