FIELD

The FIELD Command option manipulates one or more specified fields in the Current Mesh Object

For all points in the specified point set, we compose the field value with the specified composition function. The composition functions allowed are currently asinh and log. So, for example, if ‘i’ is in the point set and asinh is the composition function, we have the assignment:

field(i) = asinh(field(i)).

The field /mfedraw command causes a binary dump of the specified fields to two files in the mfedraw input format. mfedraw is a graphics package for visualizing moving piecewise linear functions of two variables, such as those originally encountered in Moving Finite Elements. The files are named ‘root1.bin’ and ‘root2.bin’, where ‘root’ is the root file name argument. Because the graphics data are a function of two variables, you must supply two orthonormal vectors (x1,y1,z1) and (x2,y2,z2) which specify the graphics coordinate axes. More precisely, given 3D coordinates (x,y,z), the 2D graphic coordinates will then be (x *x1+y *y1+z *z1 , x *x2+y *y2+z *z2). So, for example, the choice:

/x1,y1,z1/x2,y2,z2/ = /1.,0.,0./0.,1.,0./

causes the ‘z’ coordinate to be discarded while the ‘x’ and ‘y’ coordinates are unchanged.

The field /scale option scales the field values of the specified points. scale option can take on the values normalize, multiply, and divide. If normalize is specified, we multiply all the field values by factor/(fieldmax-fieldmin), where ‘fieldmax’ and ‘fieldmin’ are the maximum and minimum values taken over the point set. This has the effect of normalizing the field so that the new difference between the maximum and minimum values is equal to factor. If multiply is specified, we multiply all the field values in the point set by factor. If divide is specified, we divide all the field values in the point set by factor.

The field /volavg option, for all the members of the point set and for all specified fields, replaces the point field values with values that represent the average of the field(s) over the control volumes associated with the points. The averaging option specifies what kind of control volume is to be used; the choices are voronoi and median. iterations is an integer that specifies a repeat count for how many times this procedure is to be performed on the field(s). The affect of this process is to broaden and smooth the features of the field(s), similar to the effect of a diffusion process. The voronoi choice, unlike the median. choice, produces a diffusive effect independent of mesh connectivity. However, again unlike the median. choice, it requires that the mesh be Delaunay, or incorrect results will occur.

FORMAT:

field /compose/composition function/ifirst,ilast,istride/field list/

field /mfedraw/root file name/x1,y1,z1/x2,y2,z2/field list/

field/scale/scale option/factor/ifirst,ilast,istride/ field list /

field /volavg/averaging option/iterations/ifirst,ilast,istride/filed list/

EXAMPLES:

 field/compose/asinh/1,0,0/field/scale/normalize/4.field/volavg/voronoi/4/1