Error with tf(): # of poles (0) < # of zeros (1)

[Mildred]

Hi,

Why isn't it possible to have more zeros than poles ?

octave:1> sysout(tf([1 0], [1]))
error: # of poles (0) < # of zeros (1)
error: evaluating if command near line 79, column 3
error: called from `tf' in file `/usr/share/octave/3.0.1/m/control/system/tf.m'
error: evaluating argument list element number 1

I know this represents a non-causal system. But even if we can't build
it, it doesn't prevent us to represent it.


Last thing, why can't we build system like this (like in matlab):

	s = tf('s')
	sys = 1 / (1 + s)

Thanks

Mildred

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Mildred Ki'lya
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