User Manual

There are many different Matlab commands within Libisis. These include basic commands, such as taking the exponential of a dataset, through to integration and plotting commands. The following is an online user manual for the matlab interface of the Libisis software.

Overview

There are many different object types within Libisis used to store experimental data. Once an object is created, functions exist to manipulate the data contained within. The most common objects for plotting and data manipulation are IXTdataset_1d, IXTdataset_2d and IXTdataset_3d objects. IXTrunfile objects contain all raw data from a run.

IXTdataset_1d objects store signal and error information against one dimension (the x axis). Label and titling information is also stored. IXTdataset_2d objects also contain a second dimension (the y axis). As would be expected IXTdataset_3d objects contain yet another (z) dimension. IXTpolygons contains a list of shapes with signal data that can be plotted. All relevant data pertaining to a run can be stored in an IXTrunfile object. The object can be thought of as an array of IXTdataset_2d objects with a lot of additional information. IXTdataset_1d, IXTdataset_2d and IXTrunfile have fully implemented and similar functions, IXTdataset_3d and IXTpolygons are a special case and do not have many of the data manipulation functions as of yet.

Data is read into these objects (using methods described below) and can then be manipulated using many different tools and functions described in this documentation.

General Behaviour

Most functions share a general behaviour outlined here

Data Manipulation Functions

Input and Output Functions

Below are just a few of the possible read and write functions, other formats can also be used.

set_path, set_inst. set_ext, ass.

getspectra, getspectrum - Read in spectra from IXTraw_file objects or from RAW files

read_ascii, write_ascii - Read or write to text files

read_points, write_points - Read or write to text files, forcing data to be point data

read_hist, write_hist - Read or write to text files, forcing data to be histogram data

read_slice, read_cut, read_mask - Special functions to read from other formats

read_nxs write_nxs- Read and write from Nexus file format

Homer - Information about using Homer to import data into Libisis

Binary Operators

Binary operators such as +, -, *, etc. are used to perform arithmetic operations between datasets and/or numbers

Elementary Functions

Elementary functions act on each signal element identically

log, exp - logarithmic functions

sin, cos, tan - trigonomic functions

sinh, cosh, tanh - hyperbolic functions

Data Manipulation Functions

shift, shift_x, shift_y, shift_xy - Shift data along an independent axis

scale, scale_x, scale_y - Scale one of the independent axes

flip, flip_x, flip_y - Reverse the data in a dataset

Rebin Functions

Three different methods exist for rebinning a function. Rebin will rebin the data into user defined bins. Rebunch will bunch together a user defined number of bins. Regroup rebins data using a minimum binwidth given by the user but insures that the new bins are coincident with the existing bins.

rebin, rebin_x, rebin_y, rebin_xy

rebunch, rebunch_x, rebunch_y, rebunch_xy

regroup, regroup_x, regroup_y, regroup_xy

High Level Functions

deriv1x, deriv2x, deriv1y, deriv2y, deriv1, deriv2 - Takes derivatives of a dataset

integrate_x, integrate_y, integrate_xy, integrate - Integrates a dataset between user defined limits

smooth - Smooths out signal data to avoid small, sharp deviations

interp_x, interp_y, interp - Interpolates data onto a different set of points

unspike - Removes any large spikes from the data

fit - Fitting data to known functions and giving curves of best fit

func_eval - Evaluate a function at the given x and y data points

Special Functions

Special functions are used to transform data between different types.

contract - Turn an array of IXTdataset_2d objects into a single IXTdataset_2d object

expand_d1d, expand_listd1d, expand_d2d, expand_listd2d - Expand single objects into many objects

oned_to_twod - Convert an IXTdataset_1d into an IXTdataset_2d

hist2point, hist2point_x, hist2point_y - Convert between histogram and point data

noisify - Add noise to a dataset.

Graphics

Using Default Properties and Name Tags

Default properties and name tags are an integral part of Libisis graphics. They allow greater control of plots and it is particularly important to know about them when building applications on top of the Libisis structure. Names and tags can be used to easily identify and set properties for plots.