Functions

Function1D

class pndl::Function1D : public std::enable_shared_from_this<Function1D>

Interface to represent functions of a single variable.

Subclassed by pndl::Constant, pndl::Difference1D, pndl::Polynomial1D, pndl::Sum1D, pndl::Tabulated1D

Public Functions

virtual ~Function1D() = default
virtual double operator()(double x) const = 0

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

inline double evaluate(double x) const

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

virtual double integrate(double x_low, double x_hi) const = 0

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

Constant

class pndl::Constant : public pndl::Function1D

Implements a function which is a constant value everywhere.

Public Functions

inline Constant(double value)
Parameters

value – Value of the function.

~Constant() = default
inline virtual double operator()(double) const final override

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

inline virtual double integrate(double x_low, double x_hi) const final override

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

Polynomial1D

class pndl::Polynomial1D : public pndl::Function1D

A function of a single variable, represented by polynomial coefficients.

Public Functions

Polynomial1D(const std::vector<double> &coeffs)
Parameters

coeffs – Vector containing all of the polynomial coefficients.

~Polynomial1D() = default
virtual double operator()(double x) const final override

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

virtual double integrate(double x_low, double x_hi) const final override

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

inline std::size_t order() const

Returns the order of the polynomial.

inline double coefficient(std::size_t i) const

Returns the coefficient for the ith order term.

Parameters

i – Order of the term.

Tabulated1D

class pndl::Tabulated1D : public pndl::Function1D

Interface to represent functions of a single variable which are represented by a tabulation (TAB1 in ENDF).

Public Functions

Tabulated1D(const std::vector<uint32_t> &NBT, const std::vector<Interpolation> &INT, const std::vector<double> &x, const std::vector<double> &y)
Parameters

  • NBT – Vector of the breakpoint location.

  • INT – Vector of the interpolations for each segment.

  • x – Vector containing the x grid.

  • y – Vector contianing the y grid.

Tabulated1D(Interpolation interp, const std::vector<double> &x, const std::vector<double> &y)
Parameters

  • interp – Interpolation method used for all points.

  • x – Vector of all x points.

  • y – Vector of all y points.

~Tabulated1D() = default
inline virtual double operator()(double x) const final override

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

inline virtual double integrate(double x_low, double x_hi) const final override

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

inline const std::vector<uint32_t> &breakpoints() const

Returns a vector of the locations in the grid where the interpolation method changes.

inline const std::vector<Interpolation> &interpolation() const

Returns a vector of the interpolation methods for each segment of the grid.

inline const std::vector<double> &x() const

Returns a vector of all x points.

inline const std::vector<double> &y() const

Returns a vector of all y points.

inline double min_x() const

Returns the lowest x value.

inline double max_x() const

Returns the highest x value.

void linearize(double tolerance = 0.001)

Linearizes the function to be linearly interpolable to within the given tolerance.

Parameters

tolerance – Maximum relative absolute error for linear interpolation. The default tolerance is 0.001, or 0.1%.

Sum1D

class pndl::Sum1D : public pndl::Function1D

Class to represent a function which is a sum of two other functions.

Public Functions

inline Sum1D(std::shared_ptr<Function1D> term1, std::shared_ptr<Function1D> term2)
Parameters

  • term1 – Pointer to the function for the first term.

  • term2 – Pointer to the function for the second term.

inline virtual double operator()(double x) const final override

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

inline virtual double integrate(double x_low, double x_hi) const final override

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

inline const Function1D &term_1() const

Returns the first function in the sum.

inline const Function1D &term_2() const

Returns the second function in the sum.

Difference1D

class pndl::Difference1D : public pndl::Function1D

Class to represent a function which is the difference of two other functions.

Public Functions

inline Difference1D(std::shared_ptr<Function1D> term1, std::shared_ptr<Function1D> term2)

Function will be evaluated as term1(x) - term2(x).

Parameters

  • term1 – Pointer to the function for the first term.

  • term2 – Pointer to the function for the second term.

inline virtual double operator()(double x) const final override

Evaluates the function for a given value.

Parameters

x – Value at which to evaluate the function.

inline virtual double integrate(double x_low, double x_hi) const final override

Computes the definite integral of the function between two values.

Parameters

  • x_low – Lower bound of integration.

  • x_hi – Upper bound of integration.

inline const Function1D &term_1() const

Returns the first function in the difference.

inline const Function1D &term_2() const

Returns the second function in the difference.