f_var4d.f90 File Reference

Multi-dimensional arrays (2D, 3D, 4D) with dimension reuse (Fortran) More...

Functions/Subroutines
program	f_var4d
subroutine	handle_err (status)

Detailed Description

Multi-dimensional arrays (2D, 3D, 4D) with dimension reuse (Fortran)

This is the Fortran equivalent of var4d.c, demonstrating multi-dimensional arrays using the Fortran 90 NetCDF API. The program creates variables of different dimensionalities (2D, 3D, 4D) that share common dimensions.

Learning Objectives:

• Understand Fortran column-major array ordering for 4D data
• Learn dimension ordering reversal between Fortran and C
• Master multi-dimensional array indexing in Fortran
• Work with atmospheric/oceanographic data structures

Critical Fortran vs C Difference:

• Fortran: temp_3d(NLON, NLAT, NLEVEL, NTIME) - fastest to slowest
• C: temp_3d[NTIME][NLEVEL][NLAT][NLON] - slowest to fastest
• NetCDF dimids: Fortran (lon, lat, level, time) vs C (time, level, lat, lon)
• Access: Fortran temp_3d(j,i,lev,t) vs C temp_3d[t][lev][i][j]

Prerequisites:

• f_simple_2D.f90 - Basic 2D arrays
• var4d.c - C equivalent (note dimension order reversal!)

Related Examples:

• var4d.c - C equivalent (IMPORTANT: dimension order reversed)
• f_coord_vars.f90 - 2D geospatial data
• f_unlimited_dim.f90 - Time-series data

Compilation:

gfortran -o f_var4d f_var4d.f90 -lnetcdff -lnetcdf

Usage:

./f_var4d
ncdump f_var4d.nc

Note

Companion code for "The NetCDF Developer's Handbook: The Authoritative Guide to Writing High-Performance Programs for Scientific Data Management, Second Edition" (https://www.amazon.com/dp/B0H7Q1Z75L)

Author

Edward Hartnett, Intelligent Data Design, Inc.

Date

2026

Function/Subroutine Documentation

f_var4d()

program f_var4d

handle_err()

subroutine f_var4d::handle_err

(

integer, intent(in)

status

)