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DC T - Determine Tilt axis

(7/1/85)

PURPOSE

WARNING: This program is obsolete!! It will be left for reasons of reproducibility of old calculations. Determine the orientation of the tilT axis from coordinates of marker particles (or small features) in micrographs of tilted and untilted specimen, stored in document files. The tilt axis direction is determined in the untilted and in the tilted view relative to a line connecting the first two coordinates cotained in the corresponding document file. The document files contain two registers (x and y of each coordinate)

USAGE

.OPERATION: DC T X10,X11

.MICROGRAPH NUMBERS O DEG, TILTED: 3451,3450
[ENTER THE MICROGRAPH NUMBERS]

.LONG OUTPUT (Y/N) (DEF:Y): N
[If "Y" is answered all single angles determined from all measurements are listed in the results file]

.MAXIMUM ANGLE TO REFERENCE: 70
[Enter maximum angle relative to the reference line. As the arcsin of this angle is calculated a maximum angle smaller than <90deg>-<estimated error> has to be entered to avoid an argument >1 for arcsin.

.UPPER BOUND FOR ANGULAR (INPUT) ERROR: 20
[Enter error estimate for angle determined from the comparison of just 2 lines.]

.MINIMUM LENGTH: 2.5
[Enter minimum line length. Lines connecting points closer to each other then the minimum length are excluded from the calculation.

.DOC1: DOC051
[Enter name of docfile cotaining marker coordinates from untilted micrograph]

.DOC2: DOC052
[Enter name of docfile containig marker coordinates in tilted micrograph.]

The program writes:
TILT ANGLE CALCULATED FROM n MEASUREMENTS: theta STANDART DEVIATION: d

.TILT ANGLE (0 IF CALCULATED ONE IS TO BE USED): 0
[Enter tilt angle overwrite calculated one or 0]

NOTES

  1. The direction of the tilt axis is determined relative to a reference line that is defined by the first two coordinates (first two lines) found in the document file that contains marker coordinates. The calculations are done by triangulations. Only the absolute value of the tilt angle is determined.

  2. Not Distributed!

SUBROUTINES

ATILTAX3, WINKEL5, WINKELT, TILTANG, CALCERR

CALLER

VTIL2

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