VT1422A Command Reference 249Chapter 7
ALGorithm
Note If <alg_name> specifies an undefined algorithm, ALG:TIME? returns 0. This can be
used to determine whether algorithm <alg_name> is defined.
This command forces algorithms to run internally. If an algorithm contains a run-time
error, no data can be returned and the command will not complete (will "hang").
•When Accepted: Before INIT only.
•Returned Value: numeric value. The type is float32
•Send with VXIplug&play Function: hpe1422_cmdReal64_Q(...)

ALGorithm:FUNCtion:DEFine

ALGorithm:FUNCtion:DEFine ’<function_name>’,<range>,<offset>,
<func_data> defines a custom function that can be called from within a custom
algorithm. See “Generating User Defined Functions” on page 487 for full information.
Parameters

Comments •By providing this custom function capability, the VT1422A's algorithm

language can be kept simple in terms of mathematical capability. This increases
speed. Rather than having to calculate high-order polynomial approximations
of non-linear functions, this custom function scheme loads a pre-computed
look-up table of values into memory. This method allows computing virtually
any transcendental or non-linear function in only 17 µs. Resolution is 16 bits.
•<function_name> is a global identifier and cannot be the same as a previously
define global variable. A user function is globally available to all defined algorithms.
•Values are generated for <range>, <offset>, and <func_data> with a program
supplied with the VT1422A. It is provided in C-SCPI and BASIC forms.
For full information, see Appendix F "Generating User Defined Functions" on
page 487.
Parameter
Name Parameter
Type Range of
Values Default
Units
function_name string valid 'C' identifier
(if not already defined in 'GLOBALS') none
range numeric (float32) see comments none
offset numeric (float32) see comments none
func_data 512 element array of
uint16 see comments none