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GF - General Filter - quasi optical Fourier Filtration

(8/8/96)

PURPOSE

Masks out Fourier coefficients from input file in the vicinity of specified reflections, and transfers these into the output Fourier file.

SEE ALSO

GF C [general filter - condensed Fourier]

USAGE

.OPERATION: GF

.INPUT FILE: FOU001
[Enter name of file containing Fourier transforms to be filtered.]

.OUTPUT FILE: OUT001
[Enter name of file where output transform is to be stored.]

.FPR IN FILE: FLT001/*/#
[Enter filename if reflections are stored (from previous 'WT' run

Enter '*' if reflection information is from terminal or batch input stream, and not to be saved

Enter '#' if reflection information is from terminal of batch input stream, and to be saved after termination of the operation.

See below for these less frequently used options and the subsequent input format. In the following, it is assumed that an existing reflection file had been specified.]

.WINDOW SIZE: 3
[Enter size of square window to be used for masking. Note that the maximum is 9x9.]

Explanation of options '*' and '#'.

A filter parameter file is not available. All information on mask positions, modifying amplitude factor, and modifying phase shift have to be supplied externally, either from the terminal, or from the batch file.

Only for '#':

.FPROUT FILE: FLT001
[Enter name of file where filter parameter values supplied are to be saved for any subsequent 'GF' or 'FL' operation. The file has the same format as the file generated by the 'WT' operation (see 'WT' for detailed information).]
.WINDOW SIZE, NO. OF REFLECTIONS: 3,33
[Enter size of square window to be used for masking, and number of reflections to be entered.]

.MASK POS. (KX,KY), INDEX(H,K), AND WEIGHT(MOD,PHASE):

 
               1  43 -56   2  -4    2.0  90.0                 
               2  21 -28   1  -2                              

[Enter running number, Fourier grid coordinates, corresponding index pair, modifying amplitude factor, and modifying phase shift. The latter two may be left out, in which case they default to 1.0, 0.0. Note that the running numbers have to be in sequence. If they are not in sequence, you will get the message: "DATA OUT OF ORDER. REPEAT THIS ONE"]:

.CORRECTIONS?(Y/N): Y/N
[Enter 'N' if input was OK. Enter 'Y' if you want to correct one or more input lines. In the latter case, enter, for each incorrect line, number, Fourier grid coordinates, corresponding index pair, modifying amplitude factor, and modifying phase shift just in the same format as before. Enter a carriage return to terminate the corrections.]

NOTES

  1. The entire quasi-optical filtration procedure is documented in FILTER.DOC.

  2. Instead of the quasi-optical filtration, the so-called delta filtration may be used by (1) following 'WT' directly with 'RD D', or (2) by using 'GF C' followed by 'RD'. Both pathways are equivalent, except that 'GF C' allows transfer function correction.

SUBROUTINES

FILTG, FILTM, GSORT

CALLER

FOUR1

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