Special Functions

Some special functions exist that are useful when writing scripts that use Libisis

Contract Functions

These functions are used to contract an array of datasets into a single dataset.

>> wwout = contract(ww)

• ww is an array of IXTdataset_2d objects
• wwout is a single IXTdataset_2d object
• Two datasets must have matching x dimensions
• Each element of ww will be appended to the y dimension in the previous ww

For instance, if a dataset has ww(1).x = [1, 2, 3, 4] ww(1).y = [1, 2, 3, 4] ww(2).x = [1, 2, 3, 4] ww(2).y = [6, 7, 8] then wwout will be a dataset with wwout.x = [1, 2, 3, 4] and wwout.y = [1, 2, 3, 4, 6, 7, 8].

Expand Functions

These functions are used to expand a single IXTdataset_2d into an array of datasets.

>> wwout = expand_d2d(ww)
>>wwout = expand_listd2d(ww, list)

• Input is an IXTdataset_2d object
• Output is an IXTdataset_2d object
• Output will be an array, each element containing just one y value
• If list is given, only the y indicies in list will be expanded

For instance, if a dataset ww has y values ww.y = [32, 44, 55, 66] and list was [2, 3] then wwout will be a 2 element array of IXTdataset_2d objects with wwout(1).y = 44 and wwout(2).y = 55

>> wout = expand_d1d(ww)
>> wout = expand_listd1d(ww, list)

• Input is an IXTdataset_2d object
• Output is an IXTdataset_1d object
• Output will be an array, each element pertaining to one y row in the input
• If list is give, only the y indicies in list will be expanded

Conversion Functions

Conversion functions convert from one object type or data type to another

>> wwout = oned_to_twod(w)

• Input is an array of IXTdataset_1d objects
• Output is an IXTdataset_2d object or array of IXTdataset_2d objects
• Output will contain one y row for each element of the input
• y values will be [1, 2, 3 ...]
• x values in output will be the same as input
• Signal values in output will be the same as input
• If possible, the output dataset will be contracted to a single IXTdataset_2d object

>> wout = hist2point(w)
>> wwout = hist2point_x(ww)
>> wwout = hist2point_y(ww)

• Converts one dimension (x or y) from histogram data to point data

Functions to Aid Plotting

Standard functions exist to help with plotting

>>[xlab, ylab] = make_label(w)
>> [xlab, ylab, zlab] = make_label(ww)

• xlab is the label for the x axis
• ylab is the label for the y axis
• zlab is the label for the z axis
• w is an IXTdataset_1d object
• ww is an IXTdataset_2d object

Noisify

Noisify is a function used to add random noise to a dataset. It is good for testing fit functions etc.

>> w= noisify(w)
>> w = noisify(w, factor)
>> w = noisify(w,'poison')

• w may be an IXTdataset_1d or IXTdataset_2d object
• Output will be the same as input
• Noise will have a gaussian distribution unless given the 'poison' command
• Standard deviation = factor * (maximum signal value)
• Default factor is 0.1
• Mean value at a point in the poison distribution method is the y value.