## Institut für Astronomie und Astrophysik## Abteilung AstronomieSand 1, D-72076 Tübingen, Germany |

pfold

- Name
- Purpose
- Category
- SYNTAX:
- Input Parameters
- Keyword Parameters
- SETUP:
- Output Parameters
- Side Effects
- Example
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pfold

folds data set(s) with certain period.

cafe

pfold[,range] [,subgroup][,group][,/stderror][,/add]

range - (optional) Defines range of data points to fold. This can be either: - Data point range, denoted by the data point number: <n1>[-], while , are positive numbers. Data point numbers start from zero. Open intervals can be represented with a "*" instead of the number. If only one number is given, a single data point will be referenced. If <val2> is less than all but the interval <val2>.. are referenced. - X value range, denoted by float point numbers: <val1>- , while , represents X values defining the interval to reference. Open intervals can be represented with a * instead of the value. If <val2> is less than <val1> all but the interval <val2>.. is referenced. - Vector of data point indices. The vector is denoted with [val,val,...,val] (indgen may be used also). - Boolean expressions with X/Y values. All values for which this expression is true are referenced. The expression may contain algebraic formulas combined with comparison operators "lt", "le", "eq", "gt", "ge" as used in IDL comparisons. For each data point a keyword is defined which has meaning and can be used for the boolean expression: x - The x-column value. y - The y-column value. error - The error column value. selected - True when the data point is selected. def - True when the data point is defined. x1 - Multi column first column value. x2 - Multi column second column value. x3 - Multi column third column value. To avoid interference with functions which also can be used a lower/upper case distinction is made. IDL funktions should be upper case. Default is to fold the entire data set. subgroup - (optional) The data set (subgroup) for which the model should be applied. This can be either the subgroup number or the file name representing the data set. It is possible to set more than one subgroup, either with numbers in brackets ([]) separated with ","; or denoting filenames with wildcards ("*"). Default are all subgroups in currently used group. group - (optional) The data group for which folding should applied. Default is the current group. Must be in range [0..29].

add - Do not overwrite existing subgroups (0) but use the next free one in current result group.

period - The period to fold the data with. Should be initialized with the set command. If not defined the user will be prompted for. nbins - Number of bins to use for folding. Default: 20. time0 - Use this instead of first x value as start time. dt - Width of each time bin. Default is difference between first two x values. tolerance - parameter defining the lower limit for the gap length; the reference is the time difference between the first and second entry in the time array; tolerance defines the maximum allowed relative deviation from this reference bin length; default: 1e-8; this parameter is passed to timegap (see timgap.pro for further explanation). stderror - Compute profile error by checking the standard deviation for each bin instead using error propagation of data errors. May be used to get information about intrinsic profile variations. events - Consider input to contain events only. In this case only the time (x) axis is used and folded as single events. To work properly the data sets must not contain any gaps which are not acknowledged by to be outside of the good time interval (s.b.). gti - Good time interval (for events only). Must be 2-D array with of the form: gti[2,*]. It defines the start (gti[0,*]) and stop (gti[1,*]) time of event times (x) to be used for the pfold process. If not given it will be computed under following assumptions: 1.) start and stop of each data set define the outer gti boundary. 2.) ignored data points define inner gti boundaries. pdot - Take period derivative into account. If a single value is given this one will be computed. If pdot is of the form pdot = [a,b] then the period derivative will be scanned from in the range a..b. The number of steps are defined with pdotnum (s.b.). pddot - Second derivative of period to be taken into account. time0 - Epoch for folding, needed when usind pdot/pddot.

All data points given as input are summed up within a histogram according their x value modulo a period. The period must be set before.

Creates/Overrides first subgroup in the result group. If /add is used a new subgroup will be created.

> set, period=2000. > pfold -> fold all data in current group with a period of 2000.

$Id: cafe_pfold.pro,v 1.19 2005/02/15 10:40:40 goehler Exp $

Last modified by pro2html on 2005 February 16 at 04:17 UTC

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Jörn Wilms (wilms@astro.uni-tuebingen.de)

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