gnuplot> set term png
gnuplot> set size 0.5,1
gnuplot> set output "mumu.png"
gnuplot> set multiplot
multiplot> set origin 0,0
multiplot> plot sin(x)
multiplot> set origin 0.5,0
multiplot> plot cos(x)
multiplot> unset multiplot
gnuplot> unset output

ってやるとsin(x)の画像しか出力されないんだけどどうして？