Conditionals

## 4.1 Conditionals

Gnucap behavioral modeling conditionals are an extension of the “AC” and “DC” Spice source parameters.
The extensions ...

1. There are more choices, including an “else”.
2. They apply to all elements (primitive components).
3. Each section can contain functions and options.

The following are available:

`AC`
  AC analysis only.
`DC`
  DC (steady state) value.
`OP`
  OP analysis.
`TRAN`
  Transient analysis.
`FOUR`
  Fourier analysis only.
`ELSE`
  Anything not listed.
`ALL`
  Anything not listed.

A value or function with no conditional keyword is equivalent to `ALL`. For SPICE compatibility, use only `DC`, `AC`, or nothing.
They are interpreted like a “switch” statement. In case of a conflict, the last one applies. A set of precedence rules applies when some keys are missing. It is SPICE compatible, to the extent the features overlap.

OP analysis
  OP, DC, ALL, TRAN, 0
DC analysis
  DC, ALL, OP, TRAN, 0
Transient analysis
  TRAN, ALL, DC, OP, 0
Fourier analysis
  FOUR, TRAN, ALL, DC, OP, 0
AC analysis, fixed sources
  AC, 0
AC analysis, other elements
  AC, ALL, 0

### 4.1.1 Examples

`V12 1 0 AC 1 DC 3`
  This voltage source has a value of 1 for AC analysis, 3 for DC. OP, Transient, and Fourier inherit the DC value.
`R44 2 3 OP 1 ELSE 1g`
  This resistor has a value of 1 ohm for the “OP” analysis, 1 gig-ohm for anything else. This might be useful as the feedback resistor on an op-amp. Set it to 1 ohm to set the operating point, then 1 gig to measure its open loop characteristics, hiding the fact that the op-amp would probably saturate if it was really left open loop.