## 4.1 Conditionals

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

The extensions ...
- There are more choices, including an “else”.

- They apply to all elements (primitive components).

- 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.

The following table describes the precedence rules:
**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.