o — Operate on variables

Documentation

Reference

Commands

Set or transform the variables of a file using expressions.

Set values

Command	Action
`ox <expr>`	Set x values
`oy <expr>`	Set y values
`oz0 <expr>`, …	Set z0, z1, … values
`oz+`	Add a new z coordinate (prompts for name and unit)
`or0 <expr>`, …	Set file constant r0, r1, …
`or+`	Add a new file constant
`op0 <expr>`, …	Set fit parameter p0, p1, …
`op* <expr>`	Set all fit parameters to the same value
`opa`	Replace each parameter with its absolute value
`opc`	Copy parameters from another curve file

Calculus

Command	Action
`ofi`	Integrate (trapezoidal rule)
`ofs`	Cumulative sum up to the current point index
`ofd`	Differentiate (central differences)
`ofac`	Autocorrelate

ofac — autocorrelation

ofac replaces each spectrum with its autocorrelation function (discrete, unnormalized). The result has twice as many points and is symmetric around x = 0. Useful for checking periodicity or computing power spectra.

Rank-reducing operations

oi presents an interactive menu of operations that collapse each spectrum to a single value, producing a new file with ni = 1:

Option	Operation
1	One y per spectrum (first point)
2	One y total (all spectra → one value)
3	Mean ⟨y⟩
4	Standard deviation of y
5	x at maximum y
6	y at maximum y
7	x at minimum y
8	y at minimum y
9	Sum of y
10	Integral (trapezoidal)
11	x where cumulative integral first exceeds argument
13	Maximum x where y > 0
15	Center of gravity
16	Standard deviation of x
17	Correlation coefficient (x ↔ y)

Command	Action
`oixy`	Choose two columns and save as x and y
`oixyd`	Choose three columns and save as x, y, dy

Example — normalize by total intensity

0 > oi           # choose option 9 (sum) → result in file 1
1 > df           # file 1 has one value per spectrum (ni = 1)
0 > oy y/y[1,0,j]  # divide each spectrum by its integrated intensity

y[1,0,j] means: workspace 1, point 0, spectrum j — one normalisation factor per spectrum.