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DCL:GRPH2:UDPACK: Contour Routines: Explanation of Subroutines

8.2.3 UDGCLA

1.

Function

Sets the value of the contour level used by UDCNTR (or UDCNTZ) by the minimum & maximum values and step size, or by the number of levels.

2.

Call

CALL UDGCLA(XMIN,XMAX,DX)

3.

Explanation of Parameters

XMIN, XMAX	(R)	The minimum and maximum values of the contour levels. The levels do not necessarily need to have conveniently rounded numbers.
DX	(R)	When DX < 0, uses DX as the step size.
		When DX=0, inquires 'NLEV' and generates approximately NLEV contour levels.
		When DX > 0, generates approximately INT(ABS(DX)) contour levels.

4.

Notes

(a)

Must be XMIN != XMAX.

(b)

The contour level is set as the step size specified by DX multiplied by an integer factor.

(c)

The labels for the contours are generated by the subroutine UDLABL.  The format used in this case can be inquired/changed using UDQFMT/UDSFMT (see Section 8.2.9).

(d)

There are 2 types of contours; the major line and the minor line. The major line is a labeled contour, and the minor line is not labeled. (However, by setting the internal variable 'LABEL' to .FALSE., the major lines will also have no labels. The initial value is .TRUE..) The line index of the major line is specified by the internal variable 'INDXMJ'. (The initial value is 3.) The character height for the label of the major line is specified by the internal variable 'RSIZEL'. (Units in values of VC; the initial value is undefined. Here, RSIZEL inquires the internal variable 'RSIZEL1' handled by UZpGET/UZpSET.) The line index of the minor line is specified by the internal variable 'INDXMN'. (The initial value is 1.) 

(e)

When the internal variable 'LDASH' is .TRUE., the contour lines with negative contour levels are drawn using the line type of the inquired internal variable 'IDASH'. (The initial value of 'LDASH' is .TRUE.; the initial value of 'IDASH' is 3: dashed lines.) All other contour lines are drawn with line types of the inquired internal variable 'ISOLID'. (The initial value of 'ISOLID' is 1: solid line.)

(f)

The number of minor line between two major lines is specified by the internal variable 'ICYCLE'. (The initial value is 2.) In other words, one major line is drawn for a cycle of contours specified by the inquired value of 'ICYCLE', and the remaining contours in the cycle are minor lines. The contour levels of the major line is set as the step size specified by DX  multiplied by the factor 'ICYCLE'.