Snips

M=(100+a.mat*4-b.mdf*3);if v[NN]>=6;(1+((v[NN]-5)/10.0))*M;elsif v[NN]>=1;(1-(v[NN]/10.0))*M;end;
[formula 1]

(100.0+a.mat*4-b.mdf*3)*(1+(v[1749]/10.0))
[formula 2, requiring range -5~5 for your desired effect instead of original 1~10]

M=100+a.mat*4-b.mdf*3;P=1+(v[NN]/10);if P>1.5;1.5*M;elsif P>0.5;0.5*M;else;P*M;end;
[formula 3, which is formula 2 with capping]