The par('expression') option (15.6.6) allows to use algebraic expressions on the .measure lines. Every out_variable may be replaced by par('expression') using the general forms 1…9 described above. Internally par('expression') is substituted by a vector according to the rules of the B source (Chapt. 5.1). A typical example of the general form is shown below:

General form 10:

.MEASURE {DC|TRAN|AC|SP} result
+ FIND par('expression') AT=val

The measure statement

.measure tran vtest find par('(v(2)*v(1))') AT=2.3m

returns the product of the two voltages at time point 2.3 ms.

Note that a B-source, and therefore the par('...') feature, operates on values of type complex in AC analysis mode.