Provided by: libnetcdf-dev_4.1.3-7ubuntu2_amd64 
NAME
netcdf - Unidata Network Common Data Form (netCDF) library, version 3 interface
SYNOPSIS
use netcdf
Most Systems:
f90 ... -lnetcdf
CRAY PVP Systems:
f90 -dp -i64 ... -lnetcdf
LIBRARY VERSION
This document describes version 3 of Unidata netCDF data-access interface for the
Fortran-90 programming language.
character*80 nf90_inq_libvers()
character(len=80) :: nf90_inq_libvers
Returns a string identifying the version of the netCDF library, and when it was built,
like: "3.1a of Aug 22 1996 12:57:47 $".
The RCS ident(1) command will find a string like "$Id: @(#) netcdf library version 3.1a of
Sep 6 1996 15:56:26 $" in the library. The SCCS what(1) command will find a string like
"netcdf library version 3.1a of Aug 23 1996 16:07:40 $".
ROUTINE DESCRIPTIONS
All netCDF functions (except nf90_inq_libvers() and nf90_strerror()) return an integer
status. This behavior replaces the rcode argument used in previous versions of the
library. If this returned status value is not equal to nf90_noerr (zero), it indicates
that an error occurred. The possible status values are defined in the module netcdf.
function nf90_strerror(ncerr)
integer, intent(in) :: ncerr
character(len=80) :: nf90_strerror
Returns a string textual translation of the ncerr value, like "Attribute or
variable name contains illegal characters" or "No such file or directory".
function nf90_create(path, cmode, ncid)
character(len=*), intent(in) :: path
integer, intent(in) :: cmode
integer, optional, intent(in) :: initialsize
integer, optional, intent(inout) :: chunksize
integer, intent(out) :: ncid
integer :: nf90_create
(Corresponds to nccre() in version 2)
Creates a new netCDF dataset at path, returning a netCDF ID in ncid. The argument
cmode may include the bitwise-or of the following flags: nf90_noclobber to protect
existing datasets (default silently blows them away), nf90_share for synchronous
dataset updates (default is to buffer accesses), and nf90_lock (not yet
implemented). When a netCDF dataset is created, is is opened nf90_write. The new
netCDF dataset is in define mode.
The optional argument initialsize sets the initial size of the file at creation
time.
See nf__open() below for an explanation of the optional chunksize argument.
function nf90_open(path, mode, ncid, chunksize)
character(len=*), intent(in) :: path
integer, intent(in) :: mode
integer, intent(out) :: ncid
integer, optional, intent(inout) :: chunksize
integer :: nf90_open
(Corresponds to ncopn() in version 2)
Opens a existing netCDF dataset at path returning a netCDF ID in ncid. As of
NetCDF version 4.1, and if DAP support was enabled when the library was built, the
path may instead specify a DAP URL (refer to the NetCDF user's manual for details).
The type of access is described by the mode parameter, which may include the
bitwise-or of the following flags: nf90_write for read-write access (default read-
only), nf90_share for synchronous dataset updates (default is to buffer accesses),
and nf90_lock (not yet implemented).
The optional argument referenced by chunksize controls a space versus time
tradeoff, memory allocated in the netcdf library versus number of system calls.
Because of internal requirements, the value may not be set to exactly the value
requested. The actual value chosen is returned by reference. Using the value
nf90_sizehint_default causes the library to choose a default. How the system
choses the default depends on the system. On many systems, the "preferred I/O
block size" is available from the stat() system call, struct stat member
st_blksize. If this is available it is used. Lacking that, twice the system
pagesize is used. Lacking a call to discover the system pagesize, we just set
default chunksize to 8192.
The chunksize is a property of a given open netcdf descriptor ncid: it is not a
persistent property of the netcdf dataset.
function nf90_set_fill(ncid, fillmode, old_mode)
integer, intent(in) :: ncid, fillmode
integer, intent(out) :: old_mode
integer :: nf90_set_fill
Sets the fill-mode for a netCDF dataset to optimize writes under some
circumstances. The fill-mode argument, fillmode, can be either nf90_fill or
nf90_nofill. nf90_fill causes fill-values to be written into non-record variables
and into skipped-over records when writing beyond the last valid record.
nf90_nofill suspends this behavior. The default behavior corresponds to nf90_fill.
The previous fill-mode value is return in old_mode.
The fill-mode is a property of a given open netcdf descriptor ncid: it is not a
persistent property of the netcdf dataset.
function nf90_redef(ncid)
integer, intent(in) :: ncid
integer :: nf90_redef
(Corresponds to ncredf() in version 2)
Puts an open netCDF dataset into define mode, so dimensions, variables, and
attributes can be added or renamed and attributes can be deleted.
function nf90_enddef(ncid, h_minfree, v_align, v_minfree, r_align)
integer, intent(in) :: ncid
integer, optional, intent(in) :: h_minfree, v_align
integer, optional, intent(in) :: v_minfree, r_align
integer :: nf90_enddef
(Corresponds to ncendf() in version 2)
Takes an open netCDF dataset out of define mode. The changes made to the netCDF
dataset while it was in define mode are checked and committed to disk if no
problems occurred. Some data values may be written as well, see "VARIABLE
PREFILLING" below. After a successful call, variable data can be read or written
to the dataset.
The optional arguments are performance tuning parameters. They exposes internals
of the netcdf version 1 file format and may not be available on future netcdf
implementations.
The current netcdf file format has three sections, the "header" section, the data
section for fixed size variables, and the data section for variables which have an
unlimited dimension (record variables). The header begins at the beginning of the
file. The index (offset) of the beginning of the other two sections is contained in
the header. Typically, there is no space between the sections. This causes copying
overhead to accrue if one wishes to change the size of the sections, as may happen
when changing names of things, text attribute values, adding attributes or adding
variables. Also, for buffered i/o, there may be advantages to aligning sections in
certain ways.
The minfree parameters allow one to control costs of future calls to nf90_redef(),
nf90_enddef() by requesting that minfree bytes be available at the end of the
section. The h_minfree parameter sets the pad at the end of the "header" section.
The v_minfree parameter sets the pad at the end of the data section for fixed size
variables.
The align parameters allow one to set the alignment of the beginning of the
corresponding sections. The beginning of the section is rounded up to an index
which is a multiple of the align parameter. The flag value nf90_align_chunk tells
the library to use the chunksize (see above) as the align parameter. The v_align
parameter controls the alignment of the beginning of the data section for fixed
size variables. The r_align parameter controls the alignment of the beginning of
the data section for variables which have an unlimited dimension (record
variables).
The file format requires mod 4 alignment, so the align parameters are silently
rounded up to multiples of 4. The usual call, nf90_enddef(ncid) is equivalent to
nf__enddef(ncid, 0, 4, 0, 4).
The file format does not contain a "record size" value, this is calculated from the
sizes of the record variables. This unfortunate fact prevents us from providing
minfree and alignment control of the "records" in a netcdf file. If you add a
variable which has an unlimited dimension, the third section will always be copied
with the new variable added.
function nf90_sync(ncid)
integer, intent(in) :: ncid
integer :: nf90_sync
(Corresponds to ncsnc() in version 2)
Unless the nf90_share bit is set in nf90_open() or nf90_create(), accesses to the
underlying netCDF dataset are buffered by the library. This function synchronizes
the state of the underlying dataset and the library. This is done automatically by
nf90_close() and nf90_enddef().
function nf90_abort(ncid)
integer, intent(in) :: ncid
integer :: nf90_abort
(Corresponds to ncabor() in version 2)
You don't need to call this function. This function is called automatically by
nf90_close() if the netCDF dataset was in define mode and something goes wrong with
the commit. If the netCDF dataset isn't in define mode, then this function is
equivalent to nf90_close(). If it is called after nf90_redef(), but before
nf90_enddef(), the new definitions are not committed and the dataset is closed. If
it is called after nf90_create() but before nf90_enddef(), the dataset disappears.
function nf90_close(ncid)
integer, intent(in) :: ncid
integer :: nf90_close
(Corresponds to ncclos() in version 2)
Closes an open netCDF dataset. If the dataset is in define mode, nf90_enddef()
will be called before closing. After a dataset is closed, its ID may be reassigned
to another dataset.
function nf90_inquire(ncid, ndims, nvars, natts, unlimdimid, nformat)
integer, intent(in) :: ncid
integer, optional, intent(out) :: ndims, nvars
integer, optional, intent(out) :: natts, unlimdimid
integer, optional, intent(out) :: nformat
integer :: nf90_inquire
Inquire about an open netCDF dataset. ncid is the netCDF ID of the open dataset.
Upon successful return, ndims will contain the number of dimensions defined for
this netCDF dataset, nvars will contain the number of variables, natts will contain
the number of attributes, and unlimdimid will contain the dimension ID of the
unlimited dimension if one exists, or 0 otherwise. nformat will contain the format
version number, rarely needed because the library detects the format version and
behaves appropriately.
function nf90_def_dim(ncid, name, len, dimid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(in) :: len
integer, intent(out) :: dimid
integer :: nf90_def_dim
(Corresponds to ncddef() in version 2)
Adds a new dimension to an open netCDF dataset, which must be in define mode. name
is the dimension name. len is the size of the new dimension or nf90_unlimited to
define the unlimited dimension. On return, dimid will contain the dimension ID of
the newly created dimension.
function nf90_inq_dimid(ncid, name, dimid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(out) :: dimid
integer :: nf90_inq_dimid
(Corresponds to ncdid() in version 2)
Given an open netCDF dataset and dimension name, returns the dimension ID of the
netCDF dimension in dimid.
function nf90_inquire_dimension(ncid, dimid, name, len)
integer, intent(in) :: ncid, dimid
character(len=*), optional, intent(out) :: name
integer, optional, intent(out) :: len
integer :: nf90_inquire_dimension
Inquire about a dimension. name should be big enough (nf90_max_name) to hold the
dimension name as the name will be copied into your storage. The length return
parameter, len will contain the size of the dimension. For the unlimited
dimension, the returned length is the current maximum value used for writing into
any of the variables which use the dimension.
function nf90_rename_dim(ncid, dimid, name)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(in) :: dimid
integer :: nf90_rename_dim
(Corresponds to ncdren() in version 2)
Renames an existing dimension in an open netCDF dataset. If the new name is longer
than the old name, the netCDF dataset must be in define mode. You cannot rename a
dimension to have the same name as another dimension.
function nf90_def_var(ncid, name, xtype, dimids, varid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(in) :: xtype
integer, optional, dimension(:), intent(in) :: dimids
integer :: nf90_def_var
(Corresponds to ncvdef() in version 2)
Adds a new variable to a netCDF dataset. The netCDF must be in define mode. name
will be the name of the netCDF variable. xtype is the external, netCDF type of the
variable and should be one of nf90_byte, nf90_char, nf90_short, nf90_int,
nf90_float, or nf90_double, The optional dimids argument contains the dimension ID-
s of the domain of the netCDF variable and, consequently, determines the rank of
the created variable: if dimids is omitted, then the netCDF variable will be a
scalar; if dimids is a scalar, then the netCDF variable will be 1 dimensional; and
if dimids is a vector, then the netCDF variable will have rank equal to the number
of elements in dimids. varid will be set to the netCDF variable ID.
function nf90_inq_varid(ncid, name, varid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(out) :: varid
integer :: nf90_inq_varid
(Corresponds to ncvid() in version 2)
Returns the ID of a netCDF variable in varid given an open netCDF dataset and the
name of the variable.
function nf90_inquire_variable(ncid, varid, name, xtype, ndims, dimids, natts)
integer, intent(in) :: ncid, varid
character(len=*), optional, intent(out) :: name
integer, optional, intent(out) :: xtype, ndims
integer, dimension(*), optional, intent(out) :: dimids
integer, optional, intent(out) :: natts
integer :: nf90_inquire_variable
Inquire about a netCDF variable in an open netCDF dataset, given its variable ID.
On return, name will contain the name of the variable and should be capacious
enough (nf90_max_name). xtype will contain the external, netCDF type of the
variable. ndims will contain the dimensionality of the netCDF variable: if the
variable is a scalar, then size(ndims) will be zero; otherwise, size(ndims) will be
the rank of the variable and ndims will contain the dimension ID-s of the netCDF
dimensions that constitute the domain of the variable. natts will contain the
number of attributes associated with the netCDF variable.
function nf90_rename_var(ncid, varid, name)
integer, intent9in) :: ncid, varid
character(len=*), intent(in) :: newname
integer :: nf90_rename_var
(Corresponds to ncvren() in version 2)
Changes the name of a netCDF variable. If the new name is longer than the old
name, the netCDF must be in define mode. You cannot rename a variable to have the
name of any existing variable.
function nf90_put_var(ncid, varid, values, start, stride, imap)
integer, intent(in) :: ncid, varid
<<whatever>>, intent(in) :: values
integer, dimension(:), optional, intent(in) :: start
integer, dimension(:), optional, intent(in) :: stride
integer, dimension(:), optional, intent(in) :: imap
integer :: nf90_put_var
(Replaces ncvpt() in version 2)
Writes a value or values to a netCDF variable. The netCDF dataset must be open and
in data mode. values contains the value(s) what will be written to the netCDF
variable identified by ncid and varid; it may be a scalar or an array and must be
of type character, integer(kind=OneByteInt), integer(kind=TwoByteInt),
integer(kind=FourByteInt), integer(kind=EightByteInt), real(kind=FourByteReal), or
real(kind=EightByteReal). All values are converted to the external type of the
netCDF variable, if possible; otherwise, an nf90_erange error is returned. The
optional argument start specifies the starting index in the netCDF variable for
writing for each dimension of the netCDF variable. The optional argument stride
specifies the sampling stride (the interval between accessed values in the netCDF
variable) for each dimension of the netCDF variable (see COMMON ARGUMENT
DESCRIPTIONS below). The optional argument imap specifies the in-memory
arrangement of the data values (see COMMON ARGUMENT DESCRIPTIONS below).
function nf90_get_var(ncid, varid, values, start, stride, imap)
integer, intent(in) :: ncid, varid
<<whatever>>, intent(out) :: values
integer, dimension(:), optional, intent(in) :: start
integer, dimension(:), optional, intent(in) :: stride
integer, dimension(:), optional, intent(in) :: imap
integer :: nf90_get_var
(Replaces ncvgt() in version 2)
Reads a value or values from a netCDF variable. The netCDF dataset must be open
and in data mode. values will receive the value(s) what will be read from the
netCDF
variable identified by ncid and varid; it may be a scalar or an array and must be
of type character, integer(kind=OneByteInt), integer(kind=TwoByteInt),
integer(kind=FourByteInt), integer(kind=EightByteInt), real(kind=FourByteReal), or
real(kind=EightByteReal). All values are converted from the external type of the
netCDF variable, if possible; otherwise, an nf90_erange error is returned. The
optional argument start specifies the starting index in the netCDF variable for
reading for each dimension of the netCDF variable. The optional argument stride
specifies the sampling stride (the interval between accessed values in the netCDF
variable) for each dimension of the netCDF variable (see COMMON ARGUMENT
DESCRIPTIONS below). The optional argument imap specifies the in-memory
arrangement of the data values (see COMMON ARGUMENT DESCRIPTIONS below).
function nf90_inquire_attribute(ncid, varid, name, xtype, len, attnum)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
integer, optional, intent(out) :: xtype, len, attnum
integer :: nf90_inquire_attribute
Inquires about the netCDF attribute named name, of variable varid, in the open
netCDF dataset ncid. xtype will contain the external, netCDF type of the variable.
len will contain the number of elements in the attribute. attnum will contain the
attribute number.
function nf90_inq_attname(ncid, varid, attnum, name)
integer, intent(in) :: ncid, varid, attnum
character(len=*), intent(out) :: name
integer :: nf90_inq_attname
(Corresponds to ncanam() in version 2)
Gets the name of an attribute, given its variable ID and attribute number. This
function is useful in generic applications that need to get the names of all the
attributes associated with a variable because attributes are accessed by name
rather than number in all other attribute functions (the number of an attribute is
more volatile than the name because it can change when other attributes of the same
variable are deleted). The attributes for each variable are numbered from 1 (the
first attribute) to natts, where natts is the number of attributes for the
variable, as returned from a call to nf90_inquire_variable().
function nf90_put_att(ncid, varid, name, values)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
<<whatever>>, intent(in) :: values
integer :: nf90_put_att
Unlike variables, attributes do not have separate functions for defining and
writing values. This function defines a new attribute with a value or changes the
value of an existing attribute. If the attribute is new, or if the space required
to store the attribute value is greater than before, the netCDF dataset must be in
define mode. values contains the attribute values to be written; it may be a
scalar or a vector and must be of type character, integer(kind=OneByteInt),
integer(kind=TwoByteInt), integer(kind=FourByteInt), integer(kind=EightByteInt),
real(kind=FourByteReal), or real(kind=EightByteReal).
function nf90_get_att(ncid, varid, name, fIvalues)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
<<whatever>>, intent(out) :: values
integer :: nf90_get_att
(Replaces ncagt() in version 2)
Gets the value(s) of a netCDF attribute, given its variable ID and name. The
values are returned in values, which must be of type character,
integer(kind=OneByteInt), integer(kind=TwoByteInt), integer(kind=FourByteInt),
integer(kind=EightByteInt), real(kind=FourByteReal), or real(kind=EightByteReal).
Converts from the external type to the type of the receiving variable, if possible;
otherwise returns an nf90_erange error. All values of the attribute are returned,
so you must allocate enough space to hold them. If you don't know how much space
to reserve, call nf90_inquire_attribute() first to find out the length of the
attribute.
function nf90_copy_att(ncid_in, varid_in, name, ncid_out, varid_out)
integer, intent(in) :: ncid_in, varid_in
character(len=*), intent(in) :: name
integer, intent(in) :: ncid_out, varid_out
integer :: nf90_copy_att
(Corresponds to ncacpy() in version 2)
Copies an attribute from one netCDF dataset to another. It can also be used to
copy an attribute from one variable to another within the same netCDF dataset.
ncid_in is the netCDF ID of an input netCDF dataset from which the attribute will
be copied. varid_in is the ID of the variable in the input netCDF dataset from
which the attribute will be copied, or nf90_global for a global attribute. name is
the name of the attribute in the input netCDF dataset to be copied. ncid_out is
the netCDF ID of the output netCDF dataset to which the attribute will be copied.
It is permissible for the input and output netCDF ID's to be the same. The output
netCDF dataset should be in define mode if the attribute to be copied does not
already exist for the target variable, or if it would cause an existing target
attribute to grow. varid_out is the ID of the variable in the output netCDF
dataset to which the attribute will be copied, or nf90_global to copy to a global
attribute.
function nf90_rename_att(ncid, varid, name, newname)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name, newname
integer :: nf90_rename_att
(Corresponds to ncaren()
Changes the name of an attribute. If the new name is longer than the original
name, the netCDF must be in define mode. You cannot rename an attribute to have
the same name as another attribute of the same variable. name is the original
attribute name. newname is the new name to be assigned to the specified attribute.
If the new name is longer than the old name, the netCDF dataset must be in define
mode.
function nf90_del_att(ncid, varid, name)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
integer :: nf90_del_att
(Corresponds to ncadel() in version 2)
Deletes an attribute from a netCDF dataset. The dataset must be in define
mode.
COMMON ARGUMENT DESCRIPTIONS
In this section we define some common arguments which are used in the "FUNCTION
DESCRIPTIONS" section.
integer ncid
is the netCDF ID returned from a previous, successful call to nf90_open() or
nf90_create()
character(len=*) name
is the name of a dimension, variable, or attribute. It shall begin with an
alphabetic character, followed by zero or more alphanumeric characters including
the underscore (`_') or hyphen (`-'). Case is significant. The maximum allowable
number of characters is nf90_max_name. Names that begin with an underscore (`_')
are reserved for use by the netCDF interface.
integer xtype
specifies the external data type of a netCDF variable or attribute and is one of
the following: nf90_byte, nf90_char, nf90_short, nf90_int, nf90_float, or
nf90_double. These are used to specify 8-bit integers, characters, 16-bit
integers, 32-bit integers, 32-bit IEEE floating point numbers, and 64-bit IEEE
floating-point numbers, respectively.
integer dimids
is a vector of dimension ID's and defines the shape of a netCDF variable. The size
of the vector shall be greater than or equal to the rank (i.e. the number of
dimensions) of the variable (ndims). The vector shall be ordered by the speed with
which a dimension varies: dimids(1) shall be the dimension ID of the most rapidly
varying dimension and dimids(ndims) shall be the dimension ID of the most slowly
varying dimension. The maximum possible number of dimensions for a variable is
given by the symbolic constant nf90_max_var_dims.
integer dimid
is the ID of a netCDF dimension. netCDF dimension ID's are allocated sequentially
from the positive integers beginning with 1.
integer ndims
is either the total number of dimensions in a netCDF dataset or the rank (i.e. the
number of dimensions) of a netCDF variable. The value shall not be negative or
greater than the symbolic constant nf90_max_var_dims.
integer varid
is the ID of a netCDF variable or (for the attribute-access functions) the symbolic
constant nf90_global, which is used to reference global attributes. netCDF
variable ID's are allocated sequentially from the positive integers beginning with
1.
integer natts
is the number of global attributes in a netCDF dataset for the nf90_inquire()
function or the number of attributes associated with a netCDF variable for the
nf90_varinq() function.
integer start
specifies the starting point for accessing a netCDF variable's data values in terms
of the indicial coordinates of the corner of the array section. The indices start
at 1; thus, the first data value of a variable is (1, 1, ..., 1). The size of the
vector shall be at least the rank of the associated netCDF variable and its
elements shall correspond, in order, to the variable's dimensions.
integer stride
specifies the sampling interval along each dimension of the netCDF variable. The
elements of the stride vector correspond, in order, to the netCDF variable's
dimensions (stride(1)) gives the sampling interval along the most rapidly varying
dimension of the netCDF variable). Sampling intervals are specified in type-
independent units of elements (a value of 1 selects consecutive elements of the
netCDF variable along the corresponding dimension, a value of 2 selects every other
element, etc.).
imap specifies the mapping between the dimensions of a netCDF variable and the in-memory
structure of the internal data array. The elements of the index mapping vector
correspond, in order, to the netCDF variable's dimensions (imap(1) gives the
distance between elements of the internal array corresponding to the most rapidly
varying dimension of the netCDF variable). Distances between elements are
specified in type-independent units of elements (the distance between internal
elements that occupy adjacent memory locations is 1 and not the element's byte-
length as in netCDF 2).
VARIABLE PREFILLING
By default, the netCDF interface sets the values of all newly-defined variables of finite
length (i.e. those that do not have an unlimited, dimension) to the type-dependent fill-
value associated with each variable. This is done when nf90_enddef() is called. The
fill-value for a variable may be changed from the default value by defining the attribute
`_FillValue' for the variable. This attribute must have the same type as the variable and
be of length one.
Variables with an unlimited dimension are also prefilled, but on an `as needed' basis.
For example, if the first write of such a variable is to position 5, then positions 1
through 4 (and no others) would be set to the fill-value at the same time.
This default prefilling of data values may be disabled by or'ing the nf90_nofill flag into
the mode parameter of nf90_open() or nf90_create(), or, by calling the function
nf90_set_fill() with the argument nf90_nofill. For variables that do not use the
unlimited dimension, this call must be made before nf90_enddef(). For variables that use
the unlimited dimension, this call may be made at any time.
One can obtain increased performance of the netCDF interface by using this feature, but
only at the expense of requiring the application to set every single data value. The
performance enhancing behavior of this function is dependent on the particulars of the
implementation and dataset format. The flag value controlled by nf90_set_fill() is per
netCDF ID, not per variable or per write. Allowing this to change affects the degree to
which a program can be effectively parallelized. Given all of this, we state that the use
of this feature may not be available (or even needed) in future releases. Programmers are
cautioned against heavy reliance upon this feature.
MPP FUNCTION DESCRIPTIONS
Additional functions for use on SGI/Cray MPP machines (_CRAYMPP). These are used to set
and inquire which PE is the base for MPP for a particular netCDF. These are only relevant
when using the SGI/Cray ``global'' Flexible File I/O layer and desire to have only a
subset of PEs to open the specific netCDF file. For technical reasons, these functions
are available on all platforms. On a platform other than SGI/Cray MPP, it is as if only
processor available were processor 0.
To use this feature, you need to specify a communicator group and call glio_group_mpi() or
glio_group_shmem() prior to the netCDF nf90_open() and nf90_create() calls.
Note that the routines described below are Fortran-77 routines rather than Fortran-90
routines (they have an "nf_" prefix rather than an "nf90_" prefix).
integer function nf__create_mp(character*(*) path, integer cmode, integer initialsize,
integer pe, integer chunksize, integer ncid)
Like nf__create() but allows the base PE to be set.
The argument pe sets the base PE at creation time. In the MPP environment,
nf__create() and nf90_create() set the base PE to processor zero by default.
integer function nf__open_mp(character*(*) path, integer mode, integer pe, integer
chunksize, integer ncid)
Like nf__open() but allows the base PE to be set. The argument pe sets the base PE
at creation time. In the MPP environment, nf__open() and nf90_open() set the base
PE to processor zero by default.
integer function nf_inq_base_pe(integer ncid, integer pe)
Inquires of the netCDF dataset which PE is being used as the base for MPP use.
This is safe to use at any time.
integer function nf_set_base_pe(integer ncid, integer pe)
Resets the base PE for the netCDF dataset. Only perform this operation when the
affected communicator group synchronizes before and after the call. This operation
is very risky and should only be contemplated under only the most extreme cases.
ENVIRONMENT VARIABLES
NETCDF_FFIOSPEC
Specifies the Flexible File I/O buffers for netCDF I/O when executing under the UNICOS
operating system (the variable is ignored on other operating systems). An appropriate
specification can greatly increase the efficiency of netCDF I/O -- to the extent that
it can actually surpass FORTRAN binary I/O. This environment variable has been made a
little more generalized, such that other FFIO option specifications can now be added.
The default specification is bufa:336:2, unless a current FFIO specification is in
operation, which will be honored. See UNICOS Flexible File I/O for more information.
MAILING-LISTS
Both a mailing list and a digest are available for discussion of the netCDF interface and
announcements about netCDF bugs, fixes, and enhancements. To begin or change your
subscription to either the mailing-list or the digest, send one of the following in the
body (not the subject line) of an email message to "majordomo@unidata.ucar.edu". Use your
email address in place of jdoe@host.inst.domain.
To subscribe to the netCDF mailing list:
subscribe netcdfgroup jdoe@host.inst.domain
To unsubscribe from the netCDF mailing list:
unsubscribe netcdfgroup jdoe@host.inst.domain
To subscribe to the netCDF digest:
subscribe netcdfdigest jdoe@host.inst.domain
To unsubscribe from the netCDF digest:
unsubscribe netcdfdigest jdoe@host.inst.domain
To retrieve the general introductory information for the mailing list:
info netcdfgroup
To get a synopsis of other majordomo commands:
help
SEE ALSO
ncdump(1), ncgen(1), netcdf(3f).
netCDF User's Guide, published by the Unidata Program Center, University Corporation for
Atmospheric Research, located in Boulder, Colorado.