reset data
reset plot control
reset i/o
dimension 300 rows
label size 3
read mpc61b.dat  wafer probe mo1 day1 y1 mo2 day2 y2 diff
let t = mo1+(day1-1)/31.
let t2= mo2+(day2-1)/31.
x3label WAFER 138
multiplot corner coordinates 2 2 98 98
multiplot 3 2
plot y1 t subset wafer 138 and
plot y2 t2 subset wafer 138
x3label wafer 139
plot y1 t subset wafer 139 and
plot y2 t2 subset wafer 139
x3label WAFER 140
plot y1 t subset wafer 140 and
plot y2 t2 subset wafer 140
x3label WAFER 140
plot y1 t subset wafer 141 and
plot y2 t2 subset wafer 141
x3label WAFER 142
plot y1 t subset wafer 142 and
plot y2 t2 subset wafer 142
end of multiplot
. end of calculations