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SEVERAL BUFFERS AVAILABLE


Several buffers are available in Gifa. The three main buffers (for 1D, 2D and 3D) are chosen with the DIM command. Those 3 are the only one on which generic processing is available.

Other buffers are available :

DATA ADDDATA

Is a generic buffer designed to be a "second hand". It can hold 1D, 2D or 3D data-sets, accessed with GET and PUT, and can even be added to the current data-set with the ADDDATA command (single word).

FILTER, WINDOW

are two 1D buffers used to manipulate the current data-set. They are mostly designed to be used in conjunction with Maximum Entropy processing, but have some other use however.

FILTER holds an apodisation function, used with the APPLY FILTER command (only if the FILTER context is set to 2). In 2D or 3D, F1, F2 and F3 domains will be sequential in the buffer. You can design an exotic apodisation function, put it in the FILTER buffer, and use it.

WINDOW is very similar to FILTER as definition, but not as use. WINDOW is the description of valid points within the data-set (more precisely of )). Thus a null value in WINDOW indicate a point with total uncertainty. WINDOW usually holds 0.0 or 1.0 entries, but any real values are valid though negative values have little meaning. The command WINDOW permits to design the WINDOW function; by resting it to 1.0, or by "digging" holes in it. WINDOW is used by BCORR 3, MAXENT, etc... It is useful also to put to zero a certain region in a data set (for instance the water curtain in 3D).

Other buffers are available, used by the MaxEnt or the line-fitting package, see the specific documentations.

PUT, GET, SHOW, APPLY

are used to manipulate the different buffers.

PUT (P) loads the given buffer with the current data-set

GET (G) brings back the given buffer as the current data-set

SHOW (S) displays the given information in the 1D window or in the 2D window

APPLY (A) computes the result of the mathematical operation.

The buffer :

can be :
S
G
P
A
WINDOW
window used to compute the chisquare in MaxEnt processing, also used by the polynomial mode of BCORR

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FILTER {n }
Generic filter function, also used for MaxEnt Deconvolution

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DATA
data used as a second hand by MaxEnt and Linear Prediction, also used as a general purpose buffer.


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LAMB
the evolution of Lambda during MaxEnt iteration

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ENT
the evolution of Entropy during MaxEnt iteration

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CHI
the evolution of ChiSquare during MaxEnt iteration

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STEP
the evolution of Step during MaxEnt iteration

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SUM
the evolution of Sum of point of Image during MaxEnt iteration

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CONV
the evolution of Convergence during MaxEnt iteration

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RESIDUE
The residue after a MaxEnt run

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LINEFIT
The result of the last line fitting

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AMOEBA
the contours used for integration during the last 2D Paris integration

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FT
The causal Fourier transform (FTBIS) of the current data-set

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CURRENT
the current data-set (useful for comparing with SHOW)

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PLANE Fi n
the nth plane of the 3D data-set, along axis Fi (F1, F2 or F3)



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ROW n
the nth row of the 2D data-set



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COL n
the nth col of the 2D data-set



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The command SHOW uses, for some option, the value of the context SCOLOR to determine the colour to be used by the display.

The two commands GET DATA and PUT DATA permit to put aside a data set for a while and getting back to it very quickly. Note however that the size of the larger data-set that can be put aside this way is only a fourth of the larger Gifa data-set.

The PUT FILTER command (to be issued in 1D mode) has a syntax which depends on the setting of the NCHANNEL context. NCHANNEL describe how many independent channels will be considered in the filter window. If NCHANNEL is 1, then the current data-set will become the filter function. If NCHANNEL is greater than 1, then the command will prompt you for which channel to load the filter function in. This permits to build a 2D or 3D filter function (in which case, the ith channel corresponds to the ith dimension); or to build multichannel deconvolution functions for MaxEnt. If the channel index 0 is given, then the action is as in 1D.

The command PUT permits to put the content of one lower dimension buffer into a higher data-set. You can thus PUT ROW index or PUT COL index in 2D or PUT PLANE index in 3D :

Gifa> ROW 1 DIM 1 MULT 0.5 DIM 2 PUT ROW 1

will divide by 2 the first row of the data-set.


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