# Physicists Create Water Tractor Beam

Physicists at the Australian National University have created a tractor beam in water. Using a simple wave generator they can create water currents which could be used to confine oil spills, manipulate floating objects or explain rips at the beach.

Credit: ANU Multimedia Team

# C# float

A loop in C# using floating point numbers:

``` for (float f = 16777217f; f < 16777218f; f++) { }
```

```using System;

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
for (float f = 16777217f; f < 16777218f; f++)
Console.WriteLine("Hello.");
}
}
}
```

What went wrong?
The value of float f is actually 16777216, because it was rounded while storing the value.

```float f = 16777217f;
```

Let’s explain what goes wrong with the increment by showing an example:

```float f = 16777217f;
f++;
```

We would expect that f is now 16777218. Wrong!

```float f = 16777217f;
// f is now 16777216 !!
f++;
// f is still 16777216 !! (incremented by 1 but when being saved it is rounded again)
```