! piecewise-linear approximation 2
! x1=x11+x12+x13+x14+x15+x16+x17+x18+x19
! x2=x21+x22+x23+x24+x25+x26+x27+x28+x29

min 0.2x11+0.6x12+1x13+1.4x14+1.8x15+2.2x16+2.6x17+3x18+3.4x19+
0.2x21+0.6x22+1x23+1.4x24+1.8x25+2.2x26+2.6x27+3x28+3.4x29

s.t.
x11+x12+x13+x14+x15+x16+x17+x18+x19+x21+x22+x23+x24+x25+x26+x27+x28+x29>=3

x11<=0.2
x12<=0.2
x13<=0.2
x14<=0.2
x15<=0.2
x16<=0.2
x17<=0.2
x18<=0.2

x21<=0.2
x22<=0.2
x23<=0.2
x24<=0.2
x25<=0.2
x26<=0.2
x27<=0.2
x28<=0.2
end