Merge pull request #77 from njoy/feature/legendre-normalisation

Feature/legendre normalisation

src/scion/math/LegendreSeries/test/LegendreSeries.test.cpp

@@ -135,7 +135,7 @@ SCENARIO( "LegendreSeries" ) {
         CHECK( false == chunk.isSameDomain( OpenDomain< double >() ) );
       } // THEN
 
-      THEN( "a PolynomialSeries can be linearised" ) {
+      THEN( "a LegendreSeries can be linearised" ) {
 
         ToleranceConvergence< double > convergence( 0.01 );
         InterpolationTable< double > linear = chunk.linearise( convergence );

src/scion/math/SeriesBase.hpp

@@ -59,15 +59,15 @@ namespace math {
     /* methods */
 
     /**
-     *  @brief Return the Legendre coefficients
+     *  @brief Return the series coefficients
      */
     const std::vector< Y >& coefficients() const noexcept {
 
       return this->coefficients_;
     }
 
     /**
-     *  @brief Return the Legendre order
+     *  @brief Return the series order
      */
     unsigned int order() const noexcept {
 

src/scion/math/SeriesBase/src/ctor.hpp

@@ -6,6 +6,9 @@ SeriesBase() = default;
 /**
  *  @brief Constructor
  *
+ *  There must be at least 1 coefficient. Trailing zeros in the coefficients are
+ *  removed (if all are zero, a single zero coefficient will remain).
+ *
  *  @param coefficients   the coefficients of the series (from lowest to highest
  *                        order coefficient)
  *  @param domain         the domain of the series
@@ -15,4 +18,5 @@ SeriesBase( DomainVariant domain, std::vector< Y > coefficients ) :
   coefficients_( std::move( coefficients ) ) {
 
   verifyCoefficients( this->coefficients() );
+  this->trimCoefficients();
 }

src/scion/math/SeriesBase/src/trimCoefficients.hpp

@@ -1,12 +1,18 @@
 void trimCoefficients() {
 
   // this removes trailing zeros in the coefficients
+  // if all coefficients are zero, it leaves a single order 0 coefficient
+  // equal to zero
 
-  if ( 0.0 == this->coefficients().back() ) {
+  if ( Y( 0. ) == this->coefficients().back() ) {
 
     const auto iter =
     std::find_if( this->coefficients().rbegin(), this->coefficients().rend(),
-                  [] ( auto&& coefficient ) { return coefficient != 0.; } );
+                  [] ( auto&& coefficient ) { return coefficient != Y( 0. ); } );
     this->coefficients_.erase( iter.base(), this->coefficients_.end() );
+    if ( this->coefficients_.size() == 0 ) {
+
+      this->coefficients_.push_back( Y( 0. ) );
+    }
   }
 }