Definition of the domain of values
There may be nodes in a mesh whose values are not significant. To handle such meshes, PHIGURE defines a closed domain of significant values. This domain is given by the VMIN or VMAX data when the tundefined_value function is called: any node whose value is less than VMIN or greater than VMAX is ignored by the various mesh representation functions of PHIGURE. If the tundefined_value function is not called, the domain of significant values is considered to be infinite.
Definition of isovalues and associated colours
All PHIGURE functions that represent data coloured according to a level value, use defined isovalues. These isovalues are not predefined by PHIGURE. So the user must define the isovalue list and it associated colors, before using any PHIGURE function which make "representation of scientific data".
The association between isovalues and colors can be in 2 different ways :
- For isoline representation : an isoline is colored by the color associated to the isovalue number. The next figure illustrates an example of 4 isovalues V1, V2, V3 and V4 respectively associated to color index 4, color index 6, color index 8 and color index 10 : The basic color index is 4 and the step between two index is 2.
The basic color index is called first_colr and the step between 2 color index is colr_step. In order to obtain contiguous isovalue color table, choose colr_step = 1. Three functions are available to define isovalue list. The last parameters of these functions are first_colr and colr_step.