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GF C - General Filter - Condensed Fourier

(8/8/96)

PURPOSE

Masks out Fourier coefficients in the vicinity of specified fied reflections to produce condensed Fourier matrix. The masked-out reflections are stored in a data file of dimensions NSAM=(N**2+2), and NROW=NREFL+1, where N is the size of the window used and NREFL is the number of reflections excluding the F00 coefficient. The format of the file is:
H0, K0, RE(F00), 0.
HI, KI, RE(A11), IM(A11), RE(A12), IM(A12)...RE(ANN), IM(ANN)
HI, KI, RE(A11), IM(A11), RE(A12), IM(A12)...RE(ANN), IM(ANN)
where HI,KI are the indices of the Ith reflection stored as floating point values and ALM are the N**2 values of the masked Fourier coefficients. The masked file may only be used as input to 'RD' to produce a reduced Fourier file.

SEE ALSO

GF [General filter - quasi optical Fourier filtration]

USAGE

.OPERATION: GF C

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

.FPR IN FILE: FLT001/*/#
[Enter name of filter parameter file where 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 or batch input stream, and is 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 refelection file has been specified.]

.1ST AND 2ND ZERO TRANSFER RADII: 128,128
[If any reflections fall outside first zero in phase contrast function, specify radii (in Fourier units) of first two zeros between defocus rings. The program will invert the sign of the phases in the region between the first and second zero transfer radii.

If the first zero falls outside the highest-order reflection, enter 128,128 as above.]

.WINDOW SIZE: 3
[Enter size of square window to be used for masking.]

.MASKED FILE: MSK001
[Enter name of file where the condensed Fourier is to be put.]

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):

 
          XXX XXX XXX XXX XXX (XXX.X XXX.X) 
            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. See "NOTES" under 'GF'.

SUBROUTINES

FILTM

CALLER

FOUR1

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