====== "posy" Polynomial with non-integer powers ======

===== Syntax =====

  posy  c1,p1 c2,p2 ...
  posy  c1,p1 c2,p2 ... args

===== Purpose =====

Defines a transfer function by a one dimensional ``posynomial'', like
a polynomial, except that the powers are arbitrary, and usually non-integer.

===== Comments =====

There is no corresponding capability in any SPICE that I know of.

For capacitors, this function defines //charge// as a function of
voltage.  For inductors, it defines //flux// as a function of
current.

For fixed sources, it defines voltage or current as a function of
time.

Normal use of this function required positive input (voltage or
current).  The result is zero if the input is negative.  Raising a
negative number to a non-integer power would produce a complex result, 
which implies a non-causal result, which cannot be represented in a
traditional transient analysis.

The transfer function is defined by:

<code>
if (in >= 0){
  out = (c1*in^p1) + (c2*in^p2) + ....
}else{
  out = 0.
}
</code>

===== Parameters =====

|min   |Minimum output value (clipping).  (Default  = -infinity)  |
|max   |Maximum output value (clipping).  (Default  = infinity)  |
|abs   |Absolute value, truth value.  (Default = false).  If set to true, the result will be always positive.  |
|odd   |Make odd function, truth value.  (Default = false).  If set to true, negative values of x will be evaluated as out = -f(-x), giving odd symmetry.  |
|even  |Make even function, truth value.  (Default = false).  If set to true, negative values of x will be evaluated as out = f(-x), giving even symmetry.  |

===== Example =====

  E1 (2 0 1 0) posy(1 .5)
The output of E1 is the square root of its input.