Magnetic field representation in Octave

[Miss_Fire]

Homework Statement

I need to represent in Octave (using the quiver function) the magnetic field lines around a long wire which carries an electric current around the wire. The magnetic field of an infinitely long straight wire can be obtained by applying Ampere's law.

Homework Equations

The expression for the magnetic field is:

The Attempt at a Solution

I wrote a program in Octave and I obtained the folowing figure using the formula:

I'm almost sure that these couldn't be magnetic field lines, because I read somewhere that they must be circular. Any help would be much appreciated[/B]

 

[Simon Bridge]

Pay closer attention to the representation.