|
Size: 5109
Comment: Partial rewrite
|
Size: 5007
Comment: Finished rewrite
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 13: | Line 13: |
| ||'''Function Name'''||'''Meaning''' ||'''Example'''|| | ||'''Function Name'''||'''Meaning''' ||'''Example''' || |
| Line 20: | Line 20: |
| ||`int(n)` ||Round towards 0 to an integer ||`-5 = int(-5.8)`|| | ||`int(n)` ||Round towards 0 to an integer ||`-5 = int(-5.8)` || |
| Line 26: | Line 26: |
| ||`max(n,...)` ||Returns the value of the greatest argument ||`5 = max(1,.,5)` || ||`mix(n,...)` ||Returns the value of the least argument ||`1 = min(1,.,5)` || ||`mod(x,y)` ||x modulo y || || ||`real(s)` ||Convert string s into a real number || || ||`round(n)` ||Round to the nearest integer || || |
|
| Line 27: | Line 32: |
| ||`sign(n)` ||Returns -1 if n<0, 0 if n=0, and 1 if n>0 || || ||`sqrt(n)` ||Square root function || || ||`string(n)` ||Convert numeric value n into a string || || ||`strofreal(n)` ||Convert numeric value n into a string || || ||`sum(x)` ||Running sum of variable x || || ||`trunc(n)` ||Round towards 0 to an integer ||`-5 = trunc(-5.8)`|| |
|
| Line 35: | Line 46: |
| These are largely defined in terms of ''dates'' and ''times'', which have a standardized meaning. They count days (seconds) from the Stata epoch: `01jan1960 00:00:00.000`. | |
| Line 36: | Line 48: |
| ||'''Function Name'''||'''Meaning''' ||'''Output Format'''||'''Example'''|| ||`dhms(d,h,m,s)` ||Attach hour, minute, and second data to a date ||`%tc` || || ||`dmy(d,m,y)` ||Calculate a date from a year, month, and day ||`%td` || || ||`Cdhms(d,h,m,s)` ||Attach hour, minute, and second data to a date ||`%tC` || || ||`hms(h,m,s)` ||Calculate a time from an hour, minute, and second||`%tc` || || ||`Chms(h,m,s)` ||Calculate a time from an hour, minute, and second||`%tC` || || Note that `%tc` formats ignore leap seconds, while `%tC` formats do ''not''. |
||'''Function Name''' ||'''Meaning''' ||'''Output Format'''|| ||`dhms(d,h,m,s)` ||Attach hour, minute, and second data to a date ||`%tc` || ||`Cdhms(d,h,m,s)` ||Attach hour, minute, and second data to a date ||`%tC` || ||`dmy(d,m,y)` ||Calculate a date from a day, month, and year ||`%td` || ||`hms(h,m,s)` ||Calculate a time from an hour, minute, and second ||`%tc` || ||`Chms(h,m,s)` ||Calculate a time from an hour, minute, and second ||`%tC` || ||`mdy(m,d,y)` ||Calculate a date from a month, day, and year ||`%td` || ||`mdyhms(m,d,y,h,m,s)` ||Calculate a time from a year, month, day, hour, minute, and second ||`%tc` || ||`Cmdyhms(m,d,y,h,m,s)`||Calculate a time from a year, month, day, hour, minute, and second ||`%tC` || ||`y(y)` ||Convert a numeric year into the number of years since the epoch ||`%ty` || ||`yh(y,h)` ||Convert a year and halfyear into the number of half years since the epoch||`%th` || ||`ym(y,m)` ||Convert a year and month into the number of months since the epoch ||`%tm` || ||`yq(y,q)` ||Convert a year and quarter into the number of quarters since the epoch ||`%tq` || ||`yw(y,w)` ||Convert a year and week into the number of weeks since the epoch ||`%tw` || |
| Line 51: | Line 69: |
| ||'''Function Name'''||'''Meaning''' ||'''Example''' || ||`invnormal(p)` ||Inverse cumulative standard normal distribution ||`1.959964 = invnormal(1-0.05/2)`|| ||`normal(z)` ||Cumulative standard normal distribution ||`.9750021 = normal(1.96)` || ||`runiform()` ||Random number from uniform distribution from 0 to 1|| || ||`runiform(a,b)` ||Random number from uniform distribution from a to b|| || |
|
| Line 52: | Line 75: |
| ||'''Function Name'''||'''Meaning''' ||'''Example''' || ||`invnormal` ||Inverse cumulative standard normal distribution||`1.959964 = invnormal(1-0.05/2)`|| ||`normal` ||Cumulative standard normal distribution ||`.9750021 = normal(1.96)` || |
Of relevance to random values: see [[Stata/Set#Rng|set rng]] and [[Stata/Set#Seed|set seed]]. |
| Line 60: | Line 81: |
| == See also == | |
| Line 61: | Line 83: |
| [[www.stata.com/manuals/fnmathematicalfunctions.pdf|Stata mathematical functions]] | |
| Line 62: | Line 85: |
== Max == ---- == Mdy == Convert a month, day, and year into the number of days since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate long date = mdy(month, day, year) format date %td }}} ---- == Mdyhms == Convert a day, month, year, hour, minute, and second into the number of milliseconds since the Stata epoch (`01jan1960 00:00:00.000`) ''ignoring'' leap seconds. {{{ generate double datetime = mdyhms(month, day, year, hour, minute, second) format date %tc }}} See also `Cmdyhms`, which creates returns a number that should instead be formatted as `%tC` because it does ''not'' ignore leap seconds. ---- == Min == ---- == Mod == ---- == Real == ---- == Round == ---- == RUniform == '''`runiform(a,b)`''' returns a random number between `a` and `b`. If no parameters are specified, the defaults of `0` and `1` are used. Below is a demonstration for how an [[SurveySamples#Sampling_Methods|SRS sample]] can be drawn. {{{ set seed 123456 generate double r_sampled = runiform() sort r_sampled generate byte sampled = _n <= 100 }}} The return value is a [[Stata/DataTypes|double]]; it will be within `a + c(epsdouble)` and `b − c(epsdouble)`. By default, `runiform` uses the 64-bit Mersenne Twister algorithm. Alternate algorithms are available; see [[Stata/Set#Rng|set rng]]. See also [[Stata/Set#Seed|set seed]] for designing deterministic programs. ---- == Sign == ---- == SqRt == ---- == String == Alias for `strofreal`. ---- == StrOfReal == ---- == Sum == ---- == Trunc == ---- == Y == Convert a year into the number of years since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate int year = y(year) format year %ty }}} ---- == Yh == Convert a year and half year into the number of half years since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate int halfyears = yh(year, halfyear) format halfyears %th }}} ---- == Ym == Convert a year and month into the number of months since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate int months = y(year, month) format months %tm }}} ---- == Yq == Convert a year and quarter into the number of years since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate int quarters = yq(year, quarter) format quarters %tq }}} ---- == Yw == Convert a year and week into the number of weeks since the Stata epoch (`01jan1960 00:00:00.000`). {{{ generate int weeks = yw(year, week) format weeks %tw }}} |
[[https://www.stata.com/manuals/ddatetime.pdf|Stata datetimes]] |
Stata Numeric Functions
Stata supports these numeric functions in the global scope.
Contents
General Purpose
Function Name |
Meaning |
Example |
abs(n) |
Absolute value function |
|
ceil(n) |
Round up to an integer |
|
comb(n,k) |
[[Statistics/Combinations|Combinatorial function |
|
exp(n) |
Exponential function: en |
|
expm1(n) |
High precision implementation of exp(n)-1 |
|
floor(n) |
Round down to an integer |
|
int(n) |
Round towards 0 to an integer |
-5 = int(-5.8) |
invlogit(n) |
Inverse logit function |
|
ln(n) |
Natural log function |
|
logit(n) |
|
|
ln1m(n) |
High precision implementation of ln(n-1) |
|
ln1p(n) |
High precision implementation of ln(n+1) |
|
max(n,...) |
Returns the value of the greatest argument |
5 = max(1,.,5) |
mix(n,...) |
Returns the value of the least argument |
1 = min(1,.,5) |
mod(x,y) |
x modulo y |
|
real(s) |
Convert string s into a real number |
|
round(n) |
Round to the nearest integer |
|
round(n,p) |
Round to the nearest value for a given precision |
|
sign(n) |
Returns -1 if n<0, 0 if n=0, and 1 if n>0 |
|
sqrt(n) |
Square root function |
|
string(n) |
Convert numeric value n into a string |
|
strofreal(n) |
Convert numeric value n into a string |
|
sum(x) |
Running sum of variable x |
|
trunc(n) |
Round towards 0 to an integer |
-5 = trunc(-5.8) |
Date and Time Functions
These are largely defined in terms of dates and times, which have a standardized meaning. They count days (seconds) from the Stata epoch: 01jan1960 00:00:00.000.
Function Name |
Meaning |
Output Format |
dhms(d,h,m,s) |
Attach hour, minute, and second data to a date |
%tc |
Cdhms(d,h,m,s) |
Attach hour, minute, and second data to a date |
%tC |
dmy(d,m,y) |
Calculate a date from a day, month, and year |
%td |
hms(h,m,s) |
Calculate a time from an hour, minute, and second |
%tc |
Chms(h,m,s) |
Calculate a time from an hour, minute, and second |
%tC |
mdy(m,d,y) |
Calculate a date from a month, day, and year |
%td |
mdyhms(m,d,y,h,m,s) |
Calculate a time from a year, month, day, hour, minute, and second |
%tc |
Cmdyhms(m,d,y,h,m,s) |
Calculate a time from a year, month, day, hour, minute, and second |
%tC |
y(y) |
Convert a numeric year into the number of years since the epoch |
%ty |
yh(y,h) |
Convert a year and halfyear into the number of half years since the epoch |
%th |
ym(y,m) |
Convert a year and month into the number of months since the epoch |
%tm |
yq(y,q) |
Convert a year and quarter into the number of quarters since the epoch |
%tq |
yw(y,w) |
Convert a year and week into the number of weeks since the epoch |
%tw |
Statistical Functions
Function Name |
Meaning |
Example |
invnormal(p) |
Inverse cumulative standard normal distribution |
1.959964 = invnormal(1-0.05/2) |
normal(z) |
Cumulative standard normal distribution |
.9750021 = normal(1.96) |
runiform() |
Random number from uniform distribution from 0 to 1 |
|
runiform(a,b) |
Random number from uniform distribution from a to b |
|
Of relevance to random values: see set rng and set seed.