Feature/gp fast gaus opt

icarusalg/Utilities/FastAndPoorGauss.h

@@ -13,7 +13,7 @@
 // C/C++ standard library
 #include <array>
 #include <type_traits> // std::is_integral_v, std::is_signed_v
-#include <cmath> // std::sqrt()
+#include <cmath> // std::sqrt(), std::copysign(), std::abs()
 #include <cstddef> // std::size_t
 
 
@@ -103,16 +103,20 @@ class util::FastAndPoorGauss {
 
   //@{
   /// Returns the Gaussian distributed value corresponding to `u`.
-  Data_t transform(Data_t const u) const { return fSamples[indexOf(u)]; }
+  static Data_t transform(Data_t u)
+    { u -= 0.5; return std::copysign(fSamples[indexOf(std::abs(2*u))], u); }
   Data_t operator() (Data_t const u) const { return transform(u); }
   //@}
 
+  /// Returns the set of precomputed points.
+  static std::array<Data_t, N> const& samples() { return fSamples; }
+
     private:
   /// Sampled points of inverse Gaussian.
   static std::array<Data_t, N> const fSamples;
 
   /// Returns the index of the precomputed table serving the value `u`.
-  std::size_t indexOf(Data_t u) const;
+  static std::size_t indexOf(Data_t u);
 
   /// Fills the pre-sampling table.
   static std::array<Data_t, NPoints> makeSamples();
@@ -231,7 +235,7 @@ std::array<T, N> const util::FastAndPoorGauss<N, T>::fSamples
 
 // -----------------------------------------------------------------------------
 template <std::size_t N, typename T>
-std::size_t util::FastAndPoorGauss<N, T>::indexOf(Data_t u) const {
+std::size_t util::FastAndPoorGauss<N, T>::indexOf(Data_t u) {
   return static_cast<std::size_t>(u * NPoints);
 } // util::FastAndPoorGauss<>::indexOf()
 
@@ -248,7 +252,7 @@ auto util::FastAndPoorGauss<N, T>::makeSamples() -> std::array<Data_t, NPoints>
   util::UniformSequence<Data_t> extract { NPoints };
 
   for(Data_t& value: samples)
-    value = static_cast<Data_t>(TMath::ErfInverse(extract() * 2.0 - 1.0) * V2);
+    value = static_cast<Data_t>(TMath::ErfInverse(extract()) * V2);
 
   return samples;
 } // util::FastAndPoorGauss<>::makeSamples()

icarusalg/Utilities/SampledFunction.h

@@ -64,28 +64,28 @@ namespace util {
  * _M N_.
  *
  * @note Due to the implementation of `gsl::span`, its iterators are valid only
- *       while the span object is valid as well.
- *       This means that a construct like:
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
- *       for (auto it = sf.subsample(0).begin(); it != sf.subsample(0).end(); ++it)
- *         // ...
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *       will mysteriously fail at run time because `it` refers to a temporary
- *       span that quickly falls out of scope (and the end iterator refers to
- *       a different span object, too). The correct pattern is to store the
- *       subsample result before iterating through it:
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
- *       auto const& subsample = sf.subsample(0);
- *       for (auto it = subsample.begin(); it != subsample.end(); ++it)
- *         // ...
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *       or, if appliable, let the range-for loop di that for us:
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
- *       for (auto value: sf.subsample(0))
- *         // ...
- *       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *       This will not be the case any more with `std::span`, which apparently
- *       is going to satisfy the `borrowed_range` requirement.
+ * while the span object is valid as well.
+ * This means that a construct like:
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+ * for (auto it = sf.subsample(0).begin(); it != sf.subsample(0).end(); ++it)
+ *   // ...
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * will mysteriously fail at run time because `it` refers to a temporary
+ * span that quickly falls out of scope (and the end iterator refers to
+ * a different span object, too). The correct pattern is to store the
+ * subsample result before iterating through it:
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+ * auto const& subsample = sf.subsample(0);
+ * for (auto it = subsample.begin(); it != subsample.end(); ++it)
+ *   // ...
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * or, if applicable, let the range-for loop di that for us:
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+ * for (auto value: sf.subsample(0))
+ *   // ...
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * This will not be the case any more with `std::span`, which apparently
+ * is going to satisfy the `borrowed_range` requirement.
  *
  */
 template <typename XType = double, typename YType = XType>

icarusalg/Utilities/WaveformOperations.h

@@ -84,6 +84,7 @@ namespace icarus::waveform_operations {
       // --- BEGIN --- Operations relative to the baseline ---------------------
       /// @name Operations relative to the baseline
       /// @{
+
       /// Returns the current baseline.
       Sample_t baseline() const { return fBaseline; }