### GrADS Functions Sorted by Attribute

Mathematical Operations
abs()       Returns the absolute value
cdiff()     Performs a centered difference operation
exp()       Calculates the exponential
gint()      General integral
log()       Calculates the natural logarithm
log10()     Calculates the logarithm base 10
pow()       Raises the values of arg1 to the power of arg2
sqrt()      Calculates the square root
vint()      Calculates a mass-weighted vertical integral in mb pressure coordinates

Trigonometric Functions
cos()       Calculates the cosine
acos()      Calculates the inverse cosine
sin()       Calculates the sine
asin()      Calculates the inverse sine
tan()       Calculates the tangent
atan2()     Calculates the inverse tangent

Averaging and Summing
aave()      Calculates an areal average over an X-Y region (latitude-weighted)
amean()     Calculates an areal average over an X-Y region (not latitude-weighted)
asum()      Calculates the sum over an X-Y region (grid weighted)
asumg()     Calculates the sum over an X-Y region (not grid weighted)
atot()      Calculates the sum over an X-Y region (grid and latitude weighted)
ave()       Calculates an average over any dimension
gint()      General integral
mean()      Calculates an average over any dimension (not latitude weighted)
sum()       Calculates the sum over any dimension (grid weighted)
sumg()      Calculates the sum over any dimension (not grid weighted)
tmave()     Calculates a time averag while applying a mask
vint()      Calculates a mass-weighted vertical integral in mb pressure coordinates

Correlation and Regression
scorr()     Calculates the spatial correlation over an X-Y domain
tcorr()     Produces a spatial map of temporal correlation coefficients
sregr()     Calculates the linear least-squares regression over an X-Y domain
tregr()     Calculates the least-squares regression over the time domain

Meteorological Calculations
tvrh2q()    Calculates specific humidity given virtual temperature and relative humidity
tvrh2t()    Calculates temperature given virtual temperature and relative humidity
vint()      Calculates a mass-weighted vertical integral in mb pressure coordinates

Vector Operations
hcurl()     Calculates the vertical component of the curl
hdivg()     Calculates the horizontal divergence using finite differencing
mag()       Calculates the wind speed given u,v components
skip()      Sets alternating data values to missing

Grid Operations
amax()      Returns the maximum grid value over an X-Y region
amaxlocx()  Returns the the X location of the maximum grid value over an X-Y region
amaxlocy()  Returns the the Y location of the maximum grid value over an X-Y region
amin()      Returns the minimum grid value over an X-Y region
aminlocx()  Returns the the X location of the minimum grid value over an X-Y region
aminlocy()  Returns the the Y location of the minimum grid value over an X-Y region
atot()      Calculates the sum over an X-Y region (grid and latitude weighted)
cdiff()     Performs a centered difference operation
fndlvl()    Finds the vertical level at which a given value occurs in a variable
if()        Performs an if-then-else expression evaluation
lterp()     Performs bi-linear interpolation between two grids
max()       Returns the maximum value over a given grid dimension
maxloc()    Returns the grid location of the maximum value
min()       Returns the minimum value over a given grid dimension
minloc()    Returns grid location of the minimum value
skip()      Sets alternating data values to missing
smth9()     Performs a 9 point smoothing operation on gridded data

Station Data
coll2gr()   Creates a grid from a collection of station data
gr2stn()    Grid-to-station interpolator
oabin()     Bins station observations into grid cells
oacres()    Returns a gridded result that represents station data
s2g1d()     Converts a station timeseries to a 1D grid
stnave()    Calculates a time average of station data
stnmin()    Returns the minimum value over a time series of station data
stnmax()    Returns the maximum value over a time series of station data

Special Purpose
const()     Changes missing or non-missing values