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\page vector Vector example
This tutorial explains how to use the `Vector` classes from Ignition Math library.
## C++ example
### Compile the code
To compile the code, go to `ign-math/examples` and use `cmake`:
```{.sh}
git clone https://github.com/ignitionrobotics/ign-math/ -b ign-math6
cd ign-math/examples
mkdir build
cd build
cmake ..
make
```
When the code is compiled, run:
```{.sh}
./vector2_example
```
The ouput of the program:
```{.sh}
Vec2: 2 4
Vec2a: 1 2
Vec2b: 1.2 3.4
Vec2: x=2 y=4
Vec2a: x=1 y=2
Vec2b: x=1.2 y=3.4
4
2 8
3 6
1 2
2 2
2.23607
```
### Code
Create a `Vector2` called `vec2` of doubles using the typedef `Vector2d`. **The initial x and y values are zero**. The x and y component of `vec2` can be set at anytime.
\snippet examples/vector2_example.cc constructor
The `Vector2` class is a template, so you can also create a `Vector2` using `ignition::math::Vector2<double>`:
\snippet examples/vector2_example.cc constructor2
It's also possible to set initial values. Here we are using a `Vector2` of floats:
\snippet examples/vector2_example.cc constructor3
We can output the contents of each vector using `std::cout`.
\snippet examples/vector2_example.cc stdout
You can also get access to each component in the vector using the `X()`, `Y()` accessors or the `[]` operator, The operator is clamped to the range `[0, 1]`.
\snippet examples/vector2_example.cc access
The `Vector2` class overloads many common operators, such as:
\snippet examples/vector2_example.cc operators
There are also many useful function such as finding the distance between two vectors.
\snippet examples/vector2_example.cc distance
**There are more functions in Vector2. Take a look at the [API](https://ignitionrobotics.org/libs/math)**
## Ruby examples
This example will only work if the Ruby interface library was compiled and installed. Modify the `RUBYLIB` environment variable to include the Ignition Math library install path. For example, if you install to `/usr`:
```{.sh}
export RUBYLIB=/usr/lib/ruby:$RUBYLIB
```
Execute the examples:
```{.sh}
ruby vector2_example.rb
ruby vector3_example.rb
```
### Code
Create a `Vector2` of doubles using the typedef `Vector2d`. It's possible to set initial values or use another object to create a identical copy.
```{.rb}
va = Ignition::Math::Vector2d.new(1, 2)
```
You can get access to each component in the vector using the `X()`, `Y()` accessors.
```{.rb}
printf("va = %f %f\n", va.X(), va.Y())
printf("vb = %f %f\n", vb.X(), vb.Y())
printf("vc = %f %f\n", vc.X(), vc.Y())
```
The `Vector2` class overloads many common operators, such as:
```{.rb}
vb += va
printf("vb += va: %f %f\n", vb.X(), vb.Y())
```
There are also many useful functions, such as finding the distance between two vectors or normalizing a vector.
```{.rb}
vb.Normalize
printf("vb.Normalize = %f %f\n", vb.X(), vb.Y())
printf("vb.Distance(va) = %f\n", vb.Distance(va))
```
You can create vectors with 3 dimensions using the typedef `Vector3d`:
```{.rb}
v1 = Ignition::Math::Vector3d.new(0, 0, 0)
```
You can also get access to each component in the vector using the `X()`, `Y()` and `Z()` accessors:
```{.rb}
printf("v =: %f %f %f\n", v1.X(), v1.Y(), v1.Z())
```
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