Use long integers for Z parameter to avoid overflows after x1000 multiplication

lamp_mac/SALSA/salsa_combine_ws.pro

@@ -24,7 +24,7 @@ function salsa_combine_ws, wks_list
    ; convert float values to integer (after multiplying by 1000) to search unique values
    ; z_out contains the output values, zcomp the values to compare (integers or strings)
    if typename(zpar) eq 'FLOAT' then begin
-      zpar = fix(zpar*1000)
+      zpar = long64(zpar*1000)
       zcomp = zpar[uniq(zpar, sort(zpar))]
       z_out = zpar[uniq(zpar, sort(zpar))] / 1000.
    endif else begin
@@ -70,7 +70,7 @@ function salsa_combine_ws, wks_list
       ; check Z values and sum together equivalent points
       zval = pstruct.z
       if typename(zval) eq 'FLOAT' then begin
-        zval = fix(zval*1000)
+        zval = long64(zval*1000)
         zval = zval[uniq(zval, sort(zval))]
       endif