A back plate of a light emitting unit includes a bottom plate, a plurality of first extruding elements, a plurality of second extruding elements and a plurality of connecting elements. A second PLM performs complex, floating point multiplication on two input matrix columns. The first object code is created by compiling the source code of a computer program. The inclined upper wall portion of the chuckwall extends at an angle greater than the angle of the inclined lower wall portion of the chuckwall.