All PnetCDF functions (except nf90mpi_inq_libvers() and nf90mpi_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 pnetcdf.
functionnf90mpi_strerror(ncerr)
integer, intent(in) :: ncerr
character(len=80) :: nf90mpi_strerror
Returns a string textual translation of the ncerr value, like "Attribute or variable name contains
illegal characters" or "No such file or directory".
functionnf90mpi_create(comm,path,cmode,info,ncid)
integer, intent(in) :: comm
character(len=*), intent(in) :: path
integer, intent(in) :: cmode
integer, intent(in) :: info
integer, intent(out) :: ncid
integer :: nf90mpi_create
Creates a new netCDF dataset at path collectively by a group of MPI processes specified by comm,
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 is nf90_clobber, silently blows them
away), nf90_64bit_offset to create a file in the 64-bit offset format (CDF-2), as opposed to clas‐
sic format, the default, or nf90_64bit_data to create a file in the 64-bit data format (CDF-5).
Use either nf90_64bit_offset or nf90_64bit_data. The 64-bit offset format allows the creation of
very large files with far fewer restrictions than netCDF classic format, but can only be read by
the netCDF library version 3.6 or greater. Users are cautioned that files that use the 64-bit off‐
set format will not be recognized by netCDF applications linked to an earlier version of the
netCDF library than 3.6. Applications linked to version 3.6 or later will be able to transparent‐
ly access either the classic format or 64-bit offset format. The 64-bit data format allows the
creation of very large array variables. CDF-5 files currently will not be recognized by netCDF 3
or 4 library.
The argument cmode must be consistent among all MPI processes that collectively create the file.
The argument info is an MPI info object. Users can use it to supply the file access hints further
performance improvement. The hints include existing MPI-IO hints as well as hints defined and
used in PnetCDF.
When a netCDF dataset is created, it is opened in nf90_write mode. When this function returns,
the new netCDF dataset is in define mode.
functionnf90mpi_open(comm,path,mode,info,ncid)
integer, intent(in) :: comm
character(len=*), intent(in) :: path
integer, intent(in) :: mode
integer, intent(in) :: info
integer, intent(out) :: ncid
integer :: nf90mpi_open
Opens an existing netCDF dataset at path collectively by a group of MPI processes specified by
comm, returning a netCDF ID in ncid. 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).
The argument mode must be consistent among all MPI processes that collectively open the file. The
argument info is an MPI info object. Users can use it to supply the file access hints further
performance improvement. The hints include existing MPI-IO hints as well as hints defined and
used in PnetCDF.
functionnf90mpi_redef(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_redef
Puts an open netCDF dataset into define mode, so dimensions, variables, and attributes can be
added or renamed and attributes can be deleted.
functionnf90mpi_enddef(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_enddef
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. After a successful
call, variable data can be read or written to the dataset.
functionnf90mpi_sync(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_sync
Data written by PnetCDF APIs may be cached by local file system on each compute node. This API
flushes cached data by calling MPI_File_sync.
functionnf90mpi_flush(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_flush
Flush the data in the buffer.
functionnf90mpi_abort(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_abort
You don't need to call this function. This function is called automatically by nf90mpi_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 nf90mpi_close(). If it is
called after nf90mpi_redef(), but before nf90mpi_enddef(), the new definitions are not committed
and the dataset is closed. If it is called after nf90mpi_create() but before nf90mpi_enddef(),
the dataset disappears.
functionnf90mpi_close(ncid)
integer, intent(in) :: ncid
integer :: nf90mpi_close
Closes an open netCDF dataset. If the dataset is in define mode, nf90mpi_enddef() will be called
before closing. After a dataset is closed, its ID may be reassigned to another dataset.
functionnf90mpi_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 :: nf90mpi_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.
functionnf90mpi_def_dim(ncid,name,len,dimid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(in) :: len
integer, intent(out) :: dimid
integer :: nf90mpi_def_dim
Adds a new dimension to an open netCDF dataset, which must be in define mode. name is the dimen‐
sion name. len is the size of the new dimension or nf90mpi_unlimited to define the unlimited di‐
mension. On return, dimid will contain the dimension ID of the newly created dimension.
functionnf90mpi_inq_dimid(ncid,name,dimid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(out) :: dimid
integer :: nf90mpi_inq_dimid
Given an open netCDF dataset and dimension name, returns the dimension ID of the netCDF dimension
in dimid.
functionnf90mpi_inquire_dimension(ncid,dimid,name,len)
integer, intent(in) :: ncid, dimid
character(len=*), optional, intent(out) :: name
integer, optional, intent(out) :: len
integer :: nf90mpi_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.
functionnf90mpi_rename_dim(ncid,dimid,name)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(in) :: dimid
integer :: nf90mpi_rename_dim
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.
functionnf90mpi_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 :: nf90mpi_def_var
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 for CDF-1 and CDF-2 file
formats. CDF-5 defines additional external types: nf90_ubyte, nf90_ushort, nf90_uint, nf90_int64,
and nf90_uint64. 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 omit‐
ted, 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.
functionnf90mpi_inq_varid(ncid,name,varid)
integer, intent(in) :: ncid
character(len=*), intent(in) :: name
integer, intent(out) :: varid
integer :: nf90mpi_inq_varid
Returns the ID of a netCDF variable in varid given an open netCDF dataset and the name of the
variable.
functionnf90mpi_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 :: nf90mpi_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.
functionnf90mpi_rename_var(ncid,varid,name)
integer, intent9in) :: ncid, varid
character(len=*), intent(in) :: newname
integer :: nf90mpi_rename_var
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.
functionnf90mpi_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 :: nf90mpi_put_var
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), in‐teger(kind=TwoByteInt), integer(kind=FourByteInt), integer(kind=EightByteInt), real(kind=FourByte‐Real), 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 ac‐
cessed values in the netCDF variable) for each dimension of the netCDF variable (see COMMON ARGU‐
MENT DESCRIPTIONS below). The optional argument imap specifies the in-memory arrangement of the
data values (see COMMON ARGUMENT DESCRIPTIONS below).
functionnf90mpi_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 :: nf90mpi_get_var
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 charac‐ter, integer(kind=OneByteInt), integer(kind=TwoByteInt), integer(kind=FourByteInt), inte‐ger(kind=EightByteInt), real(kind=FourByteReal), or real(kind=EightByteReal). All values are con‐
verted 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 spec‐
ifies the in-memory arrangement of the data values (see COMMON ARGUMENT DESCRIPTIONS below).
functionnf90mpi_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 :: nf90mpi_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.
functionnf90mpi_inq_attname(ncid,varid,attnum,name)
integer, intent(in) :: ncid, varid, attnum
character(len=*), intent(out) :: name
integer :: nf90mpi_inq_attname
Gets the name of an attribute, given its variable ID and attribute number. This function is use‐
ful 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 func‐
tions (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 re‐
turned from a call to nf90mpi_inquire_variable().
functionnf90mpi_put_att(ncid,varid,name,values)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
<<whatever>>, intent(in) :: values
integer :: nf90mpi_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 be‐
fore, the netCDF dataset must be in define mode. values contains the attribute values to be writ‐
ten; it may be a scalar or a vector and must be of type character, integer(kind=OneByteInt), inte‐ger(kind=TwoByteInt), integer(kind=FourByteInt), integer(kind=EightByteInt), real(kind=FourByteRe‐al), or real(kind=EightByteReal).
functionnf90mpi_get_att(ncid,varid,name,fIvalues)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
<<whatever>>, intent(out) :: values
integer :: nf90mpi_get_att
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 re‐al(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
nf90mpi_inquire_attribute() first to find out the length of the attribute.
functionnf90mpi_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 :: nf90mpi_copy_att
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 at‐
tribute. 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 permissi‐
ble 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 out‐
put netCDF dataset to which the attribute will be copied, or nf90_global to copy to a global at‐
tribute.
functionnf90mpi_rename_att(ncid,varid,name,newname)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name, newname
integer :: nf90mpi_rename_att
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 as‐
signed to the specified attribute. If the new name is longer than the old name, the netCDF
dataset must be in define mode.
functionnf90mpi_del_att(ncid,varid,name)
integer, intent(in) :: ncid, varid
character(len=*), intent(in) :: name
integer :: nf90mpi_del_att
Deletes an attribute from a netCDF dataset. The dataset must be in define mode.
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