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README.md
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@ -1,6 +1,6 @@
# A minimalist calculator for fermi estimation
# A calculator for distributions, for Fermi estimation
This project is a minimalist, calculator-style DSL for fermi estimation. It can multiply, divide, add and substract scalars, lognormals and beta distributions.
This project is a minimalist, calculator-style DSL for fermi estimation. It can multiply, divide, add and substract scalars, lognormals and beta distributions, and supports variables.
## Motivation
@ -21,17 +21,17 @@ $ fermi
5000000 12000000
=> 5.0M 12.0M
* beta 1 200
1.9K 123.1K
=> 1.9K 123.1K
* 30 180
122.9K 11.7M
=> 122.9K 11.7M
/ 48 52
2.5K 234.6K
=> 2.5K 234.6K
/ 5 6
448.8 43.0K
=> 448.8 43.0K
/ 6 8
64.5 6.2K
=> 64.5 6.2K
/ 60
1.1 103.7
=> 1.1 103.7
```
Perhaps this example is more understandable with comments and better units:
@ -39,48 +39,15 @@ Perhaps this example is more understandable with comments and better units:
```
$ fermi
5M 12M # number of people living in Chicago
=> 5.0M 12.0M
* beta 1 200 # fraction of people that have a piano
1.9K 123.1K
beta 1 200 # fraction of people that have a piano
30 180 # minutes it takes to tune a piano, including travel time
122.9K 11.7M
/ 48 52 # weeks a year pianotuners work for
2.5K 234.6K
/ 6 8 # hours a day
353.9 34.1K
/ 48 52 # weeks a year that piano tuners work for
/ 5 6 # days a week in which piano tuners work
/ 6 8 # hours a day in which piano tuners work
/ 60 # minutes to an hour
5.9 568.3
=: piano_tuners_in_Chicago
piano_tuners_in_Chicago => 5.9 568.3
=: piano_tuners
```
Here is instead an example using beta distributions and variables:
```
$ fermi
1 2
=> 1.0 2.0
* 1_000_000_000
=> 1000.0M 2.0B
=: x # assign to variable
x => 1000.0M 2.0B
. # clear the stack, i.e., make it be 1
beta 1 2
=> beta 1.0 2.0
beta 12 300
=> beta 13.0 302.0
=. y # assign to variable and clear the stack (return it to 1)
y => beta 13.0 302.0
x
=> 1000.0M 2.0B
* y
=> samples 31.3M 98.2M
```
The difference between `=: x` and `=. y` is that `=.` clears the stack after the assignment.
If you type "help", you can see a small grammar:
```
@ -95,24 +62,31 @@ help
Variable assignment: =: variable_name
Variable assignment and clear stack: =. variable_name
Special:
Clear stack: clear | c | .
Print this help message: help | h
Print debug info: debug | d
Exit: exit | e
Comment: # this is a comment
Clear stack: clear | c | .
Print debug info: debug | d
Print help message: help | h
Start additional stack: operator (
Return from additional stack )
Exit: exit | e
Examples:
+ 2
/ 2.5
* 1 10 (interpreted as lognormal)
# this is a comment
/ 2.5 # this is an operation followed by a comment
* 1 10 # "low high" is interpreted as lognormal
+ 1 10
* beta 1 10
1 10 (multiplication taken as default operation)
1 10 # multiplication taken as default operation)
=: x
.
. # return the stack to 1.
1 100
+ x
# this is a comment
* 1 12 # this is an operation followed by a comment
* 1 12
* (
1 10
+ beta 1 100
)
=. y # save to variable and clear stack
exit
```
@ -120,11 +94,45 @@ help
- It's conceptually clearer to have all the multiplications first and then all the divisions
- For things between 0 and 1, consider using a beta distribution
- Because the model reads from standard input, you can pipe a model to it. For instance, try cat more/piano-tuners.f | fermi
### Command line options
You can specify the number of samples to draw when algebraic manipulations are not sufficient:
```
$ fermi -n 1000000
$ fermi -n 1_000_000
```
You also run a file with the -f option
```
$ fermi -f more/piano-tuners.fermi
```
### Integrations with linux utilities
Because the model reads from standard input, you can a model to it:
```
$ cat more/piano-tuners.fermi | fermi
```
You can make a model an executable file by running `$ chmod -x model.fermi` and then adding the following at the top!
```
#!/bin/usr/fermi -f
```
You can save a session to a logfile with tee:
```
fermi | tee -a fermi.log
```
## Different levels of complexity
The top level f.go file (400 lines) has a bunch of complexity: variables, parenthesis, samples, beta distributions. In the simple/ folder:
The top level f.go file (420 lines) has a bunch of complexity: variables, parenthesis, samples, beta distributions, number of samples, etc. In the simple/ folder:
- f_simple.go (370 lines) strips variables and parenthesis, but keeps beta distributions, samples, and addition and substraction
- f_minimal.go (140 lines) strips everything that isn't lognormal and scalar multiplication and addition, plus a few debug options.
@ -159,11 +167,14 @@ Done:
- [x] Clean up error code. Right now only needed for division
- [x] Maintain *both* a more complex thing that's more featureful *and* the more simple multiplication of lognormals thing.
- [x] Allow input with K/M/T
- [x] Document parenthesis syntax
- [x] Specify number of samples as a command line option
- [x] Figure out how to make models executable, by adding a #!/bin/bash-style command at the top?
- [x] Make -n flag work
- [x] Add flag to repeat input lines (useful when reading from files)
To (possibly) do:
- [ ] Specify number of samples as a command line option
- [ ] Document parenthesis syntax
- [ ] Add functions. Now easier to do with an explicit representation of the stakc
- [ ] Think about how to draw a histogram from samples
- [ ] Dump samples to file

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@ -3,6 +3,7 @@ package main
import (
"bufio"
"errors"
"flag"
"fmt"
"git.nunosempere.com/NunoSempere/fermi/pretty"
"git.nunosempere.com/NunoSempere/fermi/sample"
@ -101,7 +102,8 @@ const HELP_MSG = " Operation | Variable assignment | Special\n" +
const NORMAL90CONFIDENCE = 1.6448536269514727
const INIT_DIST Scalar = Scalar(1)
const N_SAMPLES = 1_000_000
var N_SAMPLES = 100_000
/* Printers */
func prettyPrintDist(dist Dist) {
@ -354,10 +356,13 @@ func parseWordsIntoOpAndDist(words []string, vars map[string]Dist) (string, Dist
// We want this as a function (rather than just be in main)
// to be able to have parenthesis/recusion, possibly functions
func runRepl(stack Stack, reader *bufio.Reader) Stack {
func runRepl(stack Stack, reader *bufio.Reader, echo_flag *bool) Stack {
replForLoop:
for {
new_line, _ := reader.ReadString('\n')
if *echo_flag {
fmt.Printf(new_line)
}
new_line_before_comments, _, _ := strings.Cut(new_line, "#")
new_line_trimmed := strings.TrimSpace(new_line_before_comments)
words := strings.Split(new_line_trimmed, " ")
@ -367,7 +372,7 @@ replForLoop:
continue replForLoop
/* Parenthesis */
case len(words) == 2 && (words[0] == "*" || words[0] == "+" || words[0] == "-" || words[0] == "/") && words[1] == "(":
new_stack := runRepl(Stack{old_dist: INIT_DIST, vars: stack.vars}, reader)
new_stack := runRepl(Stack{old_dist: INIT_DIST, vars: stack.vars}, reader, echo_flag)
combined_dist, err := operateDists(stack.old_dist, new_stack.old_dist, words[0])
if err == nil {
stack.old_dist = combined_dist
@ -408,7 +413,25 @@ replForLoop:
}
func main() {
reader := bufio.NewReader(os.Stdin)
num_samples_flag := flag.Int("n", N_SAMPLES, "Specifies the number of samples to draw when using samples")
filename := flag.String("f", "", "Specifies a file with a model to run")
echo_flag := flag.Bool("echo", false, "Specifies whether inputs should be echoed back. Useful if reading from a file.")
flag.Parse()
N_SAMPLES = *num_samples_flag
var reader *bufio.Reader = nil
if *filename != "" {
file, err := os.Open(*filename)
if err == nil {
reader = bufio.NewReader(file)
} else {
fmt.Printf("Error opening filename; reading from stdin instead\n")
}
}
if reader == nil {
reader = bufio.NewReader(os.Stdin)
}
stack := Stack{old_dist: INIT_DIST, vars: make(map[string]Dist)}
runRepl(stack, reader)
runRepl(stack, reader, echo_flag)
}

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@ -1,17 +1,11 @@
run:
go run f.go
build:
go build f.go
go build fermi.go
install: f
run:
go run fermi.go
install: fermi
rm /usr/bin/fermi
rm /usr/bin/f
sudo mv f /usr/bin/f
sudo ln -s /usr/bin/f /usr/bin/fermi
install_xl: f
rm /usr/bin/fermixl
rm /usr/bin/fxl
sudo mv f /usr/bin/fxl
sudo ln -s /usr/bin/fxl /usr/bin/fermixl
sudo mv fermi /usr/bin/fermi
sudo ln -s /usr/bin/fermi /usr/bin/f

10
more/executable-model.fermi Executable file
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@ -0,0 +1,10 @@
#!/bin/fermi -f
5M 12M # number of people living in Chicago
beta 1 200 # fraction of people that have a piano
30 180 # minutes it takes to tune a piano, including travel time
/ 48 52 # weeks a year that piano tuners work for
/ 5 6 # days a week in which piano tuners work
/ 6 8 # hours a day in which piano tuners work
/ 60 # minutes to an hour
=: piano_tuners
exit

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@ -1,9 +0,0 @@
5M 12M # number of people living in Chicago
0.002 0.01 # fraction of people that have a piano
30 180 # minutes it takes to tune a piano, including travel time
/ 48 52 # weeks a year that piano tuners work for
/ 5 6 # days a week in which piano tuners work
/ 6 8 # hours a day in which piano tuners work
/ 60 # minutes to an hour
# ^ piano tuners in Chicago

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@ -0,0 +1,9 @@
5M 12M # number of people living in Chicago
beta 1 200 # fraction of people that have a piano
30 180 # minutes it takes to tune a piano, including travel time
/ 48 52 # weeks a year that piano tuners work for
/ 5 6 # days a week in which piano tuners work
/ 6 8 # hours a day in which piano tuners work
/ 60 # minutes to an hour
=: piano_tuners
exit

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@ -10,13 +10,13 @@ import (
func PrettyPrintInt(n int) {
switch {
case math.Abs(float64(n)) >= 1_000_000_000_000:
fmt.Printf("%dT", n/1_000_000_000_000)
fmt.Printf("%.2fT", float64(n)/1_000_000_000_000.0)
case math.Abs(float64(n)) >= 1_000_000_000:
fmt.Printf("%dB", n/1_000_000_000)
fmt.Printf("%.2fB", float64(n)/1_000_000_000.0)
case math.Abs(float64(n)) >= 1_000_000:
fmt.Printf("%dM", n/1_000_000)
fmt.Printf("%.2fM", float64(n)/1_000_000.0)
case math.Abs(float64(n)) >= 1_000:
fmt.Printf("%dK", n/1_000)
fmt.Printf("%.2fK", float64(n)/1_000.0)
default:
fmt.Printf("%df", n)
}
@ -25,24 +25,24 @@ func PrettyPrintInt(n int) {
func PrettyPrintFloat(f float64) {
switch {
case math.Abs(f) >= 1_000_000_000_000:
fmt.Printf("%.1fT", f/1_000_000_000_000)
fmt.Printf("%.2fT", f/1_000_000_000_000)
case math.Abs(f) >= 1_000_000_000:
fmt.Printf("%.1fB", f/1_000_000_000)
fmt.Printf("%.2fB", f/1_000_000_000)
case math.Abs(f) >= 1_000_000:
fmt.Printf("%.1fM", f/1_000_000)
fmt.Printf("%.2fM", f/1_000_000)
case math.Abs(f) >= 1_000:
fmt.Printf("%.1fK", f/1_000)
fmt.Printf("%.2fK", f/1_000)
case math.Abs(f) <= 0.0001:
fmt.Printf("%.5f", f)
fmt.Printf("%.6f", f)
case math.Abs(f) <= 0.001:
fmt.Printf("%.4f", f)
fmt.Printf("%.5f", f)
case math.Abs(f) <= 0.01:
fmt.Printf("%.3f", f)
fmt.Printf("%.4f", f)
case math.Abs(f) <= 0.1:
fmt.Printf("%.2f", f)
fmt.Printf("%.3f", f)
default:
fmt.Printf("%.1f", f)
fmt.Printf("%.2f", f)
}
}