

h5math e "d1 + 2*d2" out.h5 foo.h5 bar.h5:blah  
In addition to input datasets, you can also use the x/y/z coordinates of each point in the expression, referenced by "x" "y" and "z" variables (for the first three dimensions) as well as a "t" variable that refers to the last dimension. By default, these are integers starting at 0 at the corner of the dataset, but the 0 option will change the x/y/z origin to the center of the dataset (t is unaffected), and the r res option will specify the "resolution", dividing the x/y/z coordinates by res.
All of the input datasets must have the same dimensions, which are also the dimensions of the output. If there are no input files, and you are defining the output purely by a mathematical formula, you can specify the dimensions of the output explicitly via the n size option, where size is e.g. "2x2x2".
Sometimes, however, you want to use only a smallerdimensional "slice" of multidimensional data. To do this, you specify coordinates in one (or more) slice dimension(s), via the xyzt options.
h Display help on the commandline options and usage. V Print the version number and copyright info for h5math. v Verbose output. a If the HDF5 output file already exists, append the data as a new dataset rather than overwriting the file (the default behavior). An existing dataset of the same name within the file is overwritten, however. e expression Specify the mathematical expression that is used to construct the output (generally in " quotes to group the expression as one item in the shell), in terms of the variables for the input datasets and the coordinates as described above. Expressions use a Clike infix notation, with most standard operators and mathematical functions (+, sin, etc.) being supported. This functionality is provided (and its features determined) by GNU libmatheval.
f filename Name of a text file to read the expression from, if no e expression is specified. Defaults to stdin. x ix, y iy, z iz, t it This tells h5math to use a particular slice of a multidimensional dataset. e.g. x uses the subset (with one less dimension) at an x index of ix (where the indices run from zero to one less than the maximum index in that direction). Here, x/y/z correspond to the first/second/third dimensions of the HDF5 dataset. The t option specifies a slice in the last dimension, whichever that might be. See also the 0 option to shift the origin of the x/y/z slice coordinates to the dataset center. 0 Shift the origin of the x/y/z slice coordinates to the dataset center, so that e.g. 0 x 0 (or more compactly 0x0) returns the central x plane of the dataset instead of the edge x plane. (t coordinates are not affected.) This also shifts the origin of the x/y/z variables in the expression so that 0 is the center of the dataset.
r res Use a resolution res for x/y/z (but not t) variables in the expression, so that the data "grid" coordinates are divided by res. The default res is 1. For example, if the x dimension has 21 grid steps, setting a res of 20 will mean that x variables in the expression run from 0.0 to 1.0 (or 0.5 to 0.5 if 0 is specified), instead of 0 to 20.
r does not affect the coordinates used for slices, which are always integers.
n size The output dataset must be the same size as the input datasets. If there are no input datasets (if you are defining the output purely by a formula), then you must specify the output size manually with this option: size is of the form MxNxLx... (with M, N, L being integers) and may be of any dimensionality. d name Write to dataset name in the output; otherwise, the output dataset is called "data" by default. Also use dataset name in the input; otherwise, the first input dataset (alphabetically) in a file is used. Alternatively, use the syntax HDF5FILE:DATASET (which overrides the d option).
Send bug reports to S. G. Johnson, stevenj@alum.mit.edu.
Written by Steven G. Johnson. Copyright (c) 2005 by the Massachusetts Institute of Technology.
h5utils  H5MATH (1)  May 23, 2005 
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