Improved evasion and forgoing your save

[Scion]

Just a simple question, and it is unlikely that the raw sufficiently covers it, but I thought I would ask anyway.

Assuming that a character has improved evasion (and has sufficient 'room' to use it :Þ) and they wish to forgo their save may they also forgo the protection of improved evasion?

Either way, I would of course like as much rules backing as possible to see the possible rules angles that may exist

Evasion and Improved Evasion
These extraordinary abilities allow the target of an area attack to leap or twist out of the way. Rogues and monks have evasion and improved evasion as class features, but certain other creatures have these abilities, too.

If subjected to an attack that allows a Reflex save for half damage, a character with evasion takes no damage on a successful save.

As with a Reflex save for any creature, a character must have room to move in order to evade. A bound character or one squeezing through an area cannot use evasion.

As with a Reflex save for any creature, evasion is a reflexive ability. The character need not know that the attack is coming to use evasion.

Rogues and monks cannot use evasion in medium or heavy armor. Some creatures with the evasion ability as an innate quality do not have this limitation.

Improved evasion is like evasion, except that even on a failed saving throw the character takes only half damage.

 

[Patryn of Elvenshae]

I don't see that you would take full damage.

On a failed save, you take half damage.

You have the option of "Voluntarily Giving up a Saving Throw, " and "accepting a spell’s result."

The result of a fireball on a character with Improved Evasion is half damage.

Now, I'd probably allow someone to do this, but I don't really see any rules support for it.

 

[Saeviomagy]

You could possibly choose to be helpless against the attack. That would deny you the use of improved evasion.

 

[Starglim]

Full damage.

A creature can voluntarily forego a saving throw and willingly accept a spell’s result.

If you refuse to take a saving throw at all (forego it), you do not fail your saving throw, thus improved evasion doesn't apply.