convolve [ parameter=value ... ] [ inputfile outputfile ] convolve [ parameter=value ... ] [ inputfile ... directory ]
Parameters are: include_vars, box_dims, kernel_cols, kernel_scale, preserve_type.
The function convolve performs a convolution of a user-supplied weighting array over the input dataset. convolve only works for 1-D and 2-D data.
The variables to be convolved. If the list is preceded by a hyphen, followed by a space, then the variables in the list are excluded from the assembled file, and all other variables in the input files are included.
Valid responses are any variable names in the input files, properly delimited (space or comma). The default is to include all variables.
The dimensions, in lines by samples, of the moving box. If the data is one dimensional, enter only one value. If the data is two dimensional, enter the line by sample coordinates.
Valid responses are any one or two integers. There is no default.
A space-separated list of the weighting elements of the box matrix. The list starts at the upper left corner of the box, and moves by row then column.
Valid responses are a space separated list of real numbers. There is no default.
A scaling factor to multiply all the elements. This allows you to input the kernel elements as integers, then normalize the convolution.
Valid responses are any real number. The default is 1.
Whether or not to preserve the variable type of the original variable.
Valid responses are [yes or no]. The default is yes.
If preserve_type=no, the data type of the output variable. For example, you can create real variable data from a box convolution on integer data.
Valid responses are [byte, short, long, real, double]. There is no default.
If preserve_type=no. The value for bad valued data.
Valid ranges of responses depend on the data type. There is no default.
This is an example of how convolve computes a moving box convolution.
zeus% printvar dummy2 include_vars : char(255) ? [] line_per_elem : char( 3) ? [yes] no list_dims : char( 3) ? [yes] no printout : char( 3) ? [no] Printvar dummy2 Page 1 x 1 2 3 4 5 2 3 4 5 6 3 4 5 6 7 4 5 6 7 8 zeus% zeus% convolve dummy2 dummy3 include_vars : char(255) ? [] x box_dims : int ( 2) ? 3 3 kernel_scale : real ? [1] .11111111111 preserve_type : char( 3) ? [yes] zeus% printvar dummy3 include_vars : char(255) ? [] line_per_elem : char( 3) ? [yes] n list_dims : char( 3) ? [yes] n printout : char( 3) ? [no] Printvar dummy3 Page 1 x 255 255 255 255 255 255 3 4 5 255 255 4 5 6 255 255 255 255 255 255 zeus%
convolve does not preserve scaling.
Last Update: $Date: 1998/05/28 18:20:16 $