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Table 2 .--Formulae relating cull avoss-seational area'^ to shape, section diameter (D) , 



and cull dimensions {VI, B) 



Shape 



Code 



Formula for area 



Rectangular 



R 



S = W-B 



Circular 



C 



S = 7T w2/4 



Elliptical • 



E 



S = TT W-B/4 



Pie-shaped 



P 



S = (tt/4) CD2/144) W/B 



Annular 



A 



S = (^/4) (W2 - b2) 



^S is measured in square feet. W and B will be converted to feet if cull is 

 specified to have been measured in inches. 



(1) A frustrum of a right paraboloid when the defect is visible on both ends 

 of the log. 



(2) A right paraboloid tangent at its vertex to the lower end of the portion 

 when the cull is visible only on the cut surface of the upper end. 



(3) A right cone with vertex at the upper cut if the cull is visible only on 

 the lower cut surface of the piece. 



Inaccurate calculation of volume and surface will result if the tree does not con- 

 form to the above abstractions. However, the magnitude of the error can be reduced by 

 closer spacing of the section measurements. If the above assortment of cull shapes does 

 not adequately approximate the cull area, the shape should be designated as R, the first 

 dimension set equal to the true cull area, and the second dimension set equal to 1. 



SUBPROGRAMS INTENDED TO BE MODIFIED OR SUPPLIED BY THE USER 



The NETVSL program calls several subprograms to perform certain calculations that 

 users may have reason to modify for local conditions or to meet specific objectives. 

 These subprograms are: 



(1) READIN, that transfers data from the card (or tape) source into the 

 appropriate storage location for the variables needed for computation. 



(2) BARKEQ, that calculates bark thickness. 



(3) VARTCF, that calculates the variable top diameter for cubic-foot volume 

 (output code 2) . 



(4) VARTBF, that does the same for board-foot volume (output codes 5 and 8). 

 (5] BRDCUL, that calculates the defect deductions for net board-foot volume. 



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