grdfile

The name of one or several 2-D grid files. (See GRID FILE FORMATS below.)

-C

Formats the report using tab-separated fields on a single line. The output is w e s n z0 z1 dx dy nx ny[ x0 y0 x1 y1 ] [ med scale ] [mean std rms] [n_nan]. The data in brackets are output only if the corresponding options -M, -L1, -L2, and -M are used, respectively. If the -I option is used, the output format is instead NF w e s n z0 z1, where NF is the total number of grids read and w e s n are rounded off (see -I).

-D[xoff[/yoff][+i]

Divide a single grid's domain (or the -R domain, if no grid given) into tiles of size dx times dy (set via -I). You can specify overlap between tiles by appending xoff[/yoff]. If the single grid is given you may use the modifier +i to ignore tiles that have no data within each tile subregion.

-F

Report grid domain and x/y-increments in world mapping format [Default is generic]. Does not apply to the -C option.

-I[dx[/dy]|b|i|r]

Report the min/max of the region to the nearest multiple of dx and dy, and output this in the form -Rw/e/s/n (unless -C is set). To report the actual grid region, select -Ir. For a grid produced by the img supplement (a Cartesian Mercator grid), the exact geographic region is given with -Ii (if not found then we return the actual grid region instead). If no argument is given then we report the grid increment in the form -Ixinc/yinc. If -Ib is given we write each grid's bounding box polygon instead.

-L[0|1|2|p|a]

Note: If the grid is geographic then each node represents a physical area that decreases with increasing latitude. We therefore report spherically weighted statistical estimates for such grids.

-M

Find and report the location of min/max z-values, and count and report the number of nodes set to NaN, if any.

-Rxmin/xmax/ymin/ymax[+r][+uunit] (more ...)

Specify the region of interest. Using the -R option will select a subsection of the input grid(s). If this subsection exceeds the boundaries of the grid, only the common region will be extracted.

-T[dz][+a[alpha]][+s]

Determine min and max z-value. If dz is provided then we first round these values off to multiples of dz. To exclude the two tails of the distribution when determining the min and max you can add +a to set the alpha value (in percent [2]): We then sort the grid, exclude the data in the 0.5*alpha and 100 - 0.5*alpha tails, and revise the min and max. To force a symmetrical range about zero, using minus/plus the max absolute value of the two extremes, append +s. We report the result via the text string -Tzmin/zmax or -Tzmin/zmax/dz (if dz was given) as expected by makecpt.

-V[level] (more ...)

Select verbosity level [c].

-f[i|o]colinfo (more ...)

Specify data types of input and/or output columns.

-^ or just -

Print a short message about the syntax of the command, then exits (NOTE: on Windows just use -).

-+ or just +

Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.

-? or no arguments

Print a complete usage (help) message, including the explanation of all options, then exits.