Susceptibility - PUBLIC METHODS

Susceptibility();

Default constructor. It is not allowed and will terminate the program.

Susceptibility

(int order, int size, double scale, System *name, char flag);

Allocates memory for order susceptibilities and their errors and calculates functional derivatives of the response of the system. The response must be defined internally in the system. The FD_VERBOSE flag causes the object to display information while calculating the susceptibilities, including the order of the susceptibility being calculated, the number of perturbations used at any given time, the perturbation times and any inaccuracies of the calculation. An asterisk (*) indicates the latter, which is followed by the derivative orders, the time point at which the error occurred and the accuracy achieved.

Parameters

Susceptibility(char *name);

Allocates memory for the number of susceptibilities specified in the binary file name and reads the data from the file. It also allocates memory for the errors, but does not read them. Susceptibilities need not be calculated if this constructor is used. If the file is not found, cannot be opened or its format is incorrect, an error is prompted and the program is terminated.

Parameters

~Susceptibility();

Deallocates the susceptibilities and their errors. It need not be called explicitly.

void WriteToBinaryFile(char *name, char flag);

Writes a binary file with the susceptibilities of all orders. It also stores information on their size and scale, and on the order of the approximation. Only one flag is accepted. If ambiguous, the errors will be written.

Parameters

void ReadBinaryErrors(char *name);

Reads a binary file and sets the errors of the susceptibilities. The latter must have been read from another file by using Susceptibility(char *name). If the file is not found, or if its format is not correct, an error is prompted and the program terminates.

Parameters

void RawToTextFile(char *name, char flag);

Writes the susceptibilities to a text file exactly in the same order as they are stored in the computer memory. The structure of the file is:

This file should be used primarily to check the correctness of the calculations. If this method is called with the flag FD_WITH_ERRORS, the last two columns are written, with the errors and the accuracy, "o" (accurate) or "*" (inaccurate). If the file cannot be created, the program terminates.

Parameters

void FirstToTextFile(char *name, char flag);

Writes the first susceptibility to a text file.

The last two columns are written only if the method is called with the flag FD_WITH_ERRORS. The last column is "o", if the specified accuracy was achieved, or "*", if not. If the file cannot be created, the program terminates.

Parameters

void SecondToTextFile(char *name, int 2nd_time, char flags);

Writes the second susceptibility (if any) to a text file.

The last two columns are written only if the method is called with the flag FD_WITH_ERRORS. The last column is "o", if the specified accuracy was achieved, or "*", if not. If the flag FD_GNUPLOT is on, a carriage return is written between real time blocks. This is required for plotting with the GNU application gnuplot. The plotting mode must be parametric. For example:

             set parametric
             splot 'file.dat' u 1:2:3

If the file cannot be created or there is no second susceptibility, the program terminates.

Parameters

void ThirdToTextFile(char *name, int 2nd_time, char flags);

Writes a section of the third susceptibility (if any) to a text file.

The first column is the fixed second perturbation time only if the flag FD_SECOND_TIME is on. The last two columns are written only if the method is called with the flag FD_WITH_ERRORS. The last column is "o", if the specified accuracy was achieved, or "*", if not. If the flag FD_GNUPLOT is on, a carriage return is written between real time blocks. This is required for plotting in parametric mode with the GNU application gnuplot. For example:

             set parametric
             splot 'file.dat' u 1:2:3

or

             splot 'file.dat' u 2:3:4

(if FD_SECOND_TIME is on). If the file cannot be created or there is no third susceptibility, the program terminates.

Parameters

void TestSums(char *name);

Calculates the integrals of the susceptibilities and writes them to stdout and to the specified text file.

Parameters

Response operator*(Signal &);

Calculates multiple convolutions of a signal (the input flux variation) with the susceptibilities of a system. The result is returned as a Response object, which contains all the orders of the response and their total sum. This sum is the approximation to the (variation of the) response of the system. The operation itself is commutative, but the method is written so that the signal must be left-multiplied. This method overloads "*". It needs not be called explicitly. For example:

             int tau=50;
             double dt=0.1;

                    // Create a step function 
                    //  of 50 points and time
                    //  increment of 0.1
             Signal sig(tau, dt);

                    // Read the suscetibilities 
                    //  of a system from a file
             Susceptibility sus("suscept.dat");

                    // Create a response object
             Response res;

                    // Calculate the response
                    //  The method 
                    //   Susceptibility::operator* 
                    //  is implicitly called
             res = sus*sig;       // NOTE: sig*sus is not defined

If the signal and the susceptibilities are not in the same scale or the number of discrete-time points is different, this method prompts an error and the program terminates.

int GetOrder();

Retrieves the order of the approximation, i.e. the number of susceptibilities in the object.

int GetSize();

Retrieves the number of discrete-time points of the approximation.

double GetTimeInc();

Retrieves the time increment used for discretizing the signals.

Copyright © 2003-2013 Antonio Sánchez Torralba
Last modified:
Monday, 04-Mar-2013 11:58:25 CET