Expressions

. 4+7            # yields 11
. sin(pi/2)      # yields 1
. y[2,0,7]       # y value of file 2, spectrum 0, point 7

3 > oy x^2         # set y := x^2 for all points in file 3
5 > op0 y[4,0,j]   # initialize p0 from values in file 4

3 > dp y<10    # show all points with y < 10
3 > mr x>0     # retain only points where x > 0
3 > md x<=0    # equivalent: delete points where x ≤ 0

8 > cc p0 + p1*t    # affine-linear fit curve for file 8

expr:
  <arithmetic_expr>
  <function_evaluation>
  resol ( <shift> )             # Dirac delta / resolution copy
  conv ( <theory>, <shift> )    # convolution with resolution
  <numeric_value>
  <variable_reference>
  t                             # running variable for curve evaluation
  <curve_reference> ( <expr> )  # e.g. c[4](x-0.2)

arithmetic_expr:
  ( <expr> )
  - <expr>                        # negation
  ! <expr>                        # boolean negation
  <expr> <bin_op> <expr>
  <expr> ? <expr> : <expr>        # conditional (lowest precedence)

numeric_value:
  <integer>                  # e.g. 8 or -17
  <floating point>           # e.g. .2, 2.72, -3.7e-3
  pi | e                     # hard-coded constants

var_label:
  k          file number in memory
  r0, r1, …  file constants
  dr0, …     errors of file constants  (not yet implemented)
  nj         number of spectra

jvar_label:     (one index: j)
  j          spectrum index
  z0, z1, …  z coordinates
  dz0, …     errors of z coordinates   (not yet implemented)
  p0, p1, …  fit parameters
  dp0, …     parameter errors
  cq0-cq2    fit quality metrics
  ni         number of data points

ivar_label:     (two indices: j, i)
  i          data point index
  x          x value
  y          y value
  dy         error of y

c              # c[k,j] with k, j from context
c[<k>]         # c[k,j] with j from context
c[<k>,<j>]     # fully specified