To make a C graphing utility that is capable of graphing functions.
The above is an example graph made by this graphing utility. It is the example file provided and shows the graph of:
- sin(x^2 + 1)
- cos(x)
- tan(x)
- (x + 1)^(x + 1)
- (x - 1)^2 + 1
- (x + 1)^3 - 1
- log(x)
This graphing utility is capable of making netpbm image files of the function(s) that the user specifies in any color in the rgb channel.
The user can specify a set of functions and graph window parameters via an input file that this utility reads then produces an output file. See the Use and Installation/Building sections for more details.
This program is free of memory leaks when fed an expected input file as verified using several test input files and valgrind.
The following commands can be used for most users to build the project:
git clone https://github.com/millipedes/C-Netpbm-Function-Grapher.git
cd C-Netpbm-Function-Grapher/
mkdir bin
make
This will put an executable file called main in bin/. This is how to build
the project.
As the image output format is netpbm which is rather uncommon, I would recommend either:
- Installing a netpbm image viewer
- Installing ImageMagick to be able to convert the output file to a .png file.
If you would like to install a viewer:
sudo apt install feh (For Debian based i.e. Ubuntu, mint, etc.)
sudo pacman -S feh (For arch based i.e. Manjaro, Endevour, Garuda etc.)
sudo xbps-install -S feh (Void)
And if you aren't on one of those distros I would imagine you are familiar with your package manager (alpine, kiss, etc.).
If you want to install ImageMagick:
sudo apt install imagemagick
sudo pacman -S imagemagick
sudo xbps-install -S imagemagick
etc.
And it is worth noting that to use ImageMagick to convert a netpbm file to a .png it would be:
convert example.ppm output_png_file.png
The program expects only one thing from the user and that is the input file. So once you build the executable you would run the program via:
./path_to/executable path_to/input_file.txt
Currently only one output file can be produced by one input file but that is on the immediate list of features to be implemented.
An example input file is as follows with comments. Note that comments cannot be in the file when sent into the utility.
One line is used to define each parameter to the given output file and always
needs to be prefaced with FILE_NAME followed with a space by the output file
name. This file will need to be terminated with an END. Within this block
In the input file, there are two types of parameters, blocks (i.e. a name that
defines a block ended with END, for example FUNC terminated by END) and
single line assignments (just one line). The following shows custom parameters
for all acceped inputs
FILE_NAME :: test.ppm // This line specifies the file name
X_MIN :: -10 // This line specifies the minimum x value that the
// graph will show
Y_MIN :: -10 // This line specifies the minimum y value that the
// graph will show
X_MAX :: 10 // This line specifies the maximum x value that the
// graph will show
Y_MAX :: 10 // This line specifies the maximum y value that the
// graph will show
/**
* There are two color options
* 1) specify 1 color and all functions will be of that color, OR
* 2) specify 1 color for each function and each function will be its
* corresponding color sequentially
* In this example the second option was chosen
*/
COLOR :: 0,35,66
COLOR :: 255,0,0
COLOR :: 0,255,0
COLOR :: 0,0,255
COLOR :: 255,0,255
END // Necessary Tag
FUNCS // Necessary Tag
/**
* In this block any number of functions can be specified.
* The valid operators are +, -, *, /, sin, cos, tan, arcsin, arccos,
arctan, log (log is only base 2 at the moment)
* The variable is whatever (minus functions above) the user specifies so
* long as it contains english Latin characters or `_`'s
*/
(x - 1)^2 + 1
(x + 1)^3 - 1
x^4
x^5
2 * x + 1
END // Necessary Tag
The above example without comments can be found in
docs/example_graph_set/example_graph.txt. Additionally by running the
command:
make run
After the project is built, it will take in the example file as input and output in the current directory the file test.ppm corresponding to the example input file.
This program uses the following context free grammar in BNF (I have left factored it for readability with respect to the parser) via an LL(1) parser to achieve the ability of reading in arbitrary user functions:
E -> T E'
E' -> (+|-) T E' | $\epsilon$
T -> F T'
T' -> (*|/) F T' | $\epsilon$
F -> (sin|cos|tan|arcsin|arccos|arctan|log)* (E) | id
id -> Variable | Double
The following features I will be implementing in the future:
- Accept Points as Input.
- Make support for calculus functions (
der/int) for trancendental functions in the context free grammar. - Relationships
- Vector Fields
- Write a better file I/O to include the ability for one input file to write to several output files.
- 3d support (very bottom of the list).
- Compilers: Principles, Techniques, & Tools Second Edition Aho, Lam, Sethi, Ullman. This book has been instrumental in my learning about interpreters, additionally I used one of their CFG's as a basic building block for the CFG used in this project.