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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