Calculate

Invokes the interpreter of arithmetic expressions for SCANs.

Format:

SPECTRA> calc$*$ulate result = vector_expr

Description:

result: A vector_id that describes where the result of the calculation is stored. See section 8 for an explanation of the term vector_id. If the resultant SCAN does not exist, it is created. If the vector_id refers to an empty slot (like y(10)), a SCAN named scan_i (scan_10) is created.

vector_expr: An arithmetic expression that contains vector_id's and also scalar arithmetic. The expressions are explained in sections 9ff and functions in sections 14ff.

e.g.:

SPECTRA> calc temp = log( ioni1/ioni2)
The y-values of ioni2 are interpolated at the x-positions of ioni1. The x-values of temp vary in a range that is covered by ioni1 and ioni2. The y-values of temp are the logarithms of the ratio of the y-values of ioni1 and the interpolated y-values of ioni2.

SPECTRA> calc x(bpu1) = x(bpu1) / 1000
The x-values of bpu1 are divided by 1000, the y-values are not changed.

The operators < and > cut on the x- and y-values.

Format:

SPECTRA> calc spec1 = spec2 > y_min

Format:

SPECTRA> calc x(spec3) = x(spec2) < x_max

Description:

Spec1 contains those points of spec2 which have y-values above y_min.

Spec2 contains those points of spec2 which have x-values below x_max.

Note that there is a verb vcalc that treats the data like vectors - whithout any interpolation. The only requirement is that all operands have the same length. See section 15.3.81 for details.