Fixing the STA issue

ReleaseNotes.md

@@ -7,6 +7,7 @@ This update removes the regions() and pairs() interface functions on the TAB1 re
 In addition, the following issues were corrected:
   - A minor bug in the rectangular matrix covariance block was corrected. The values for the row and column energies are lifted out of a larger array using the std::ranges::take and std::ranges::drop function. For the column energies, we forgot to properly end the sequence. As a result, the end() iterator of the range did not point to the end of the column energies but to the end of the covariance values, which is now corrected.
   - In MF8 MT457 DiscreteSpectrum, NT=8 (which can occur for electrons, i.e. STYP=8), was explicitly disallowed by ENDFtk. This was corrected and a new constructor reflecting this usage was added as well.
+  - The STA variable in MF1 MT451 was interpreted incorrectly and this has now been fixed. An additional isUnstable() function has been added to the interface.
 
 A few changes were also made to remove some range-v3 code in MF1 MT451. These changes have no impact on functionality.
 

python/src/section/1/451.python.cpp

@@ -70,7 +70,7 @@ void wrapSection_1_451( python::module& module, python::module& viewmodule ) {
     "    nlib           the library type\n"
     "    nmod           the modification number\n"
     "    elis           the excitation energy\n"
-    "    sta            the stability flag\n"
+    "    sta            the stability flag (whether or not the nuclide is unstable)\n"
     "    lis            the excited level number\n"
     "    liso           the isomeric state number\n"
     "    nfor           the library format version number\n"
@@ -151,11 +151,17 @@ void wrapSection_1_451( python::module& module, python::module& viewmodule ) {
     &Section::STA,
     "The stability flag"
   )
+  .def_property_readonly(
+
+    "is_unstable",
+    &Section::isUnstable,
+    "Flag to indicate whether or not the nuclide is unstable"
+  )
   .def_property_readonly(
 
     "is_stable",
     &Section::isStable,
-    "The stability flag"
+    "Flag to indicate whether or not the nuclide is stable"
   )
   .def_property_readonly(
 

python/test/MF1/Test_ENDFtk_MF1_MT451_Section.py

@@ -15,7 +15,7 @@ class Test_ENDFtk_MF1_MT451_Section( unittest.TestCase ) :
     # randomly set to test if the correct value is extracted instead of using
     # ENDF legal values
     chunk = ( ' 1.001000+3 9.991673-1          1          2          3          4 125 1451     \n'
-              ' 5.000000+0 6.000000+0          7          8          0         12 125 1451     \n'
+              ' 5.000000+0 0.000000+0          7          8          0         12 125 1451     \n'
               ' 1.300000+1 1.400000+1         15          0         17         18 125 1451     \n'
               ' 1.900000+1 0.000000+0         21          0          9         10 125 1451     \n'
               '  1-H -  1 LANL       EVAL-JUL16 G.M.Hale                          125 1451     \n'
@@ -139,7 +139,8 @@ def verify_chunk( self, chunk ) :
             self.assertEqual( 4, chunk.modification_number )
             self.assertAlmostEqual( 5.0, chunk.ELIS )
             self.assertAlmostEqual( 5.0, chunk.excitation_energy )
-            self.assertAlmostEqual( 6.0, chunk.STA )
+            self.assertAlmostEqual( 0.0, chunk.STA )
+            self.assertEqual( False, chunk.is_unstable )
             self.assertEqual( True, chunk.is_stable )
             self.assertEqual( 7, chunk.LIS )
             self.assertEqual( 7, chunk.excited_level )
@@ -175,7 +176,7 @@ def verify_chunk( self, chunk ) :
         # the data is given explicitly
         chunk = Section( zaid = 1001, awr = 0.9991673, lrp = 1,
                          lfi = 2, nlib = 3, nmod = 4,
-                         elis = 5., sta = 6., lis = 7,
+                         elis = 5., sta = 0., lis = 7,
                          liso = 8, nfor = 12, awi = 13.,
                          emax = 14., lrel = 15, nsub = 17,
                          nver = 18, temp = 19., ldrv = 21,

src/ENDFtk/section/1/451.hpp

@@ -107,9 +107,14 @@ namespace section {
     double STA() const { return std::get< 0 >( this->parameters_ ).C2(); }
 
     /**
-     *  @brief Return the stability flag
+     *  @brief Return whether or not the nuclide is unstable
+     */
+    bool isUnstable() const { return this->STA() == 1; }
+
+    /**
+     *  @brief Return whether or not the nuclide is stable
      */
-    bool isStable() const { return this->STA(); }
+    bool isStable() const { return ! this->isUnstable(); }
 
     /**
      *  @brief Return the excited level number

src/ENDFtk/section/1/451/src/ctor.hpp

@@ -32,7 +32,7 @@ Type() = default;
  *  @param[in] nlib          the library type
  *  @param[in] nmod          the modification number
  *  @param[in] elis          the excitation energy
- *  @param[in] sta           the stability flag
+ *  @param[in] sta           the stability flag (whether or not the nuclide is unstable)
  *  @param[in] lis           the excited level number
  *  @param[in] liso          the isomeric state number
  *  @param[in] nfor          the library format version number

src/ENDFtk/section/1/451/test/451.test.cpp

@@ -39,7 +39,7 @@ SCENARIO( "section::Type< 1, 451 >" ) {
       int nlib = 3;
       int nmod = 4;
       double elis = 5.;
-      double sta = 6.;
+      double sta = 0.;
       int lis = 7;
       int liso = 8;
       int nfor = 12;
@@ -178,7 +178,7 @@ std::string chunk() {
   // ENDF legal values
   return
     " 1.001000+3 9.991673-1          1          2          3          4 125 1451     \n"
-    " 5.000000+0 6.000000+0          7          8          0         12 125 1451     \n"
+    " 5.000000+0 0.000000+0          7          8          0         12 125 1451     \n"
     " 1.300000+1 1.400000+1         15          0         17         18 125 1451     \n"
     " 1.900000+1 0.000000+0         21          0          9         10 125 1451     \n"
     "  1-H -  1 LANL       EVAL-JUL16 G.M.Hale                          125 1451     \n"
@@ -220,7 +220,8 @@ void verifyChunk( const section::Type< 1, 451 >& chunk ) {
   CHECK( 4 == chunk.modificationNumber() );
   CHECK_THAT( 5.0, WithinRel( chunk.ELIS() ) );
   CHECK_THAT( 5.0, WithinRel( chunk.excitationEnergy() ) );
-  CHECK_THAT( 6.0, WithinRel( chunk.STA() ) );
+  CHECK_THAT( 0.0, WithinRel( chunk.STA() ) );
+  CHECK( false == chunk.isUnstable() );
   CHECK( true == chunk.isStable() );
   CHECK( 7 == chunk.LIS() );
   CHECK( 7 == chunk.excitedLevel() );