| 摘要 |
PURPOSE:To display a secondary curved surface as some part of a subject in an electronic computer by storing the secondary curved surface enclosed by a boundary and data on a secondary curve and boundary line on said surface, obtaining an intersection between the secondary curve an d the boundary line on said surface and displaying the secondary curve and boundary line, both of which connect intersections. CONSTITUTION:A memory means 11 for the secondary curved surface enclosed by the boundary stores a pair of constants and boundaries of an equation on the secondary curved surface, while a memory means 12 for data on the secondary curve on the secondary curved surface is a table relating to secondary curves existing in a lattice on the secondary curved surface, is composed of a flat table consisting of the longitude and circle of the secondary curve, stores constants on the plane including the longitude and circle. A boundary data memory means 13 stores dot strings on the boundary line. A means 14 for calculating an intersection between the secondary curve and boundary line on the secondary curved surface calculates the intersection between the secondary curve and boundary line on the secondary curved surface from data on the means 12 and 13, an obtained intersection controlling means 15 prepares tables for the longitude and circle of these intersections, and a means 16 for displaying the secondary curve connecting intersections and the boundary line obtains the secondary curve and boundary line connecting intersections and displays them.
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