* alterparam edits a .param value; mc_source re-expands the deck to apply it
.param rval=1k
V1 in 0 DC 1
R1 in 0 {rval}
.op
.control
  run
  print @r1[resistance]
  alterparam rval=2k
  mc_source              $ rebuild the circuit with the new .param
  op
  print @r1[resistance]
.endc
.end