The melodic minor scale is one of the most commonly used in jazz. Constructing it is easy if you already know the major scale or the dorian mode. The C major scale is comprised of the following notes C D E F G A B. The melodic minor has the following C D Eb F G A B. The only note that differs between the two scales is the third. The C major scale has a major 3rd (E) and the melodic minor scale has a minor 3rd (Eb) . Ex 1 shows the two scales up to the 15th fret.
Ex 2 is a comparison between the C dorian mode and the C melodic minor scale. Once again there is only one note difference between the two scales. This time its the 7th degree. The dorian contains the following notes C D Eb F G A Bb (minor 7th) and the melodic minor is C D Eb F G A B (major 7th).