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File kernel/src/simulationTools/TimeDiscretisation.hpp

File kernel/src/simulationTools/TimeDiscretisation.hpp#

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A time-discretisation scheme for a given interval.

Typedefs

typedef std::vector<double> TkVector#
class TimeDiscretisation
#include <TimeDiscretisation.hpp>

A time discretisation scheme.

A TimeDiscretisation object is used to discretized a given time interval. TimeDiscretisation are used:

  • in the simulation, as a user-input to discretized [t0,T]

  • in Sensor and Actuator, to define the set of time instants where the sensor or actuator must operate.

A TimeDiscretisation is defined with a starting time (t0), a time step size (h, non necessarily constant), the number of the current time step (k). The time instant values are saved in a vector tk. Depending on the way of construction of the TimeDiscretisation, all or only current and next times are saved in tk. The difference is just a question of saving memory.

Note that the TimeDiscretisation is not linked to the Model. It’s up to the user to check that the way he builds his time-discretisation fits with the t0 and T given in the model.

Main functions:

  • setCurrentTimeStep(), to set current h. This value will be used for all future time steps, until next change.

  • increment(), shift to next time step (increment k, and shift t[k] and t[k+1])

  • currentTime(), return t[k]

Construction

  • input = the complete vector tk. This defines t0, T, number of time steps and time step size (which is not necessarily constant). In this case, the whole vector is saved in the memory.

  • inputs = number of time steps, t0 and T. size h is computed with t0,T and nSteps. Only two values are saved: t[k] and t[k+1] = t[k] + h. h can be changed at any time.

  • inputs = h and t0. Only two values are saved: t[k] and t[k+1] = t[k] + h. h can be changed at any time.

  • inputs = t0 and h. Only two values are saved: t[k] and t[k+1] = t[k] + h. h can be changed at any time.

Public Functions

TimeDiscretisation(const TkVector &newTk)

constructor with tk vector of instant times values.

Parameters:

newTk – a TkVector describing the discretisation

TimeDiscretisation(double t0, double h)

constructor with the size of the default time step and t0

Parameters:

  • t0 – initial time value

  • h – the time step

TimeDiscretisation(unsigned int nSteps, double t0, double T)

constructor with the number of steps, t0 and T

Parameters:

  • nSteps – the number of steps

  • t0 – initial time value

  • T – the final time

TimeDiscretisation(double t0, const std::string &str)

Constructor with the size of the default timestep and t0.

It creates a TimeDiscretisation using GMP for all its computation

Parameters:

  • t0 – initial time value

  • str – the time step in form of a string

TimeDiscretisation(const TimeDiscretisation &td)

Copy constructor.

Parameters:

td – the TimeDiscretisation to copy

~TimeDiscretisation()#
double currentTimeStep(const unsigned int k)

get the timestep \( t_{k+1} - t_k \)

Parameters:

k – the index of the timestep

Returns:

the current time step

inline const mpf_t *currentTimeStep() const

get the timestep in gmp format

Returns:

a pointer to the timestep in mpf_t format

inline bool hConst() const

determine whether the timestep is constant

Returns:

true if the timestep is constant

inline bool hGmp() const

determine whether the TimeDiscretisation is using GMP

Returns:

true if the TimeDiscretisation is using GMP

double getTk(const unsigned int indx)

get the value of tk at step k

Parameters:

indx – the step

Returns:

a double

inline const TkVector &getTkVector() const

get the TkVector _tkV

Returns:

a reference to the TkVector _tkV

void setTkVector(const TkVector &newTk)

set the TkVector _tkV

Parameters:

newTk – the new value for _tkV

void setT0(double val)

change t0 before the simulation starts (useful for delays)

Parameters:

val – the new value for t0

void display() const

print the discretisation data to the screen

Private Functions

ACCEPT_SERIALIZATION(TimeDiscretisation)#
TimeDiscretisation()#

default constructor (private => no copy nor pass-by value)

TimeDiscretisation &operator=(const TimeDiscretisation &td)#

Assignment Operator (private => forbidden)

Parameters:

td – unused

Returns:

TimeDiscretisation&

inline double getT0() const#

Get the origin of time t0.

Returns:

the origin of time

Private Members

double _h#

Default value for the time step (tk+1 - tk)

TkVector _tkV#

vector of time values at each step (=> size = n1+n2+1 - Default size = 2 - Max size= nSteps+1)

double _t0#

Origin of time.

mpf_t _hgmp#

Timestep stored as mpf_t, for high precision computations.

mpf_t _tkp1#

Time at t_{k+1}, in mpf_t, used to compute a good timestep.

mpf_t _tk#

Time at t_{k+1}, in mpf_t, used to compute a good timestep.

mpf_t _t0gmp#

Starting time, used to compute a good timestep.

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