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Re: Cannot plot this functions

• To: mathgroup at smc.vnet.net
• Subject: [mg53863] Re: Cannot plot this functions
• From: D Herring <dherring at at.uiuc.dot.edu>
• Date: Tue, 1 Feb 2005 04:08:13 -0500 (EST)
• References: <ctfv5b$pe2$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

> I need to plot the negative derivative of this function with respect
> to Ï?. Whne I use plot it gives me the error:
> 
> function is not a machine - size real number at Ï?  =1.8622242690864824`*^-7

Sometimes, simply wrapping your expression in an Evaluate[] will 
eliminate this error.

I've had several troublesome cases where
Plot[EXPRESSION, {t,0,10}]
gave "function is not a ... at t=4..."
while
Plot[Evaluate[EXPRESSION], {t,0,10}]
works just fine.

They hint about this in the documentation, but its still easy to miss.

Hope that helps,
Daniel