function calcvid(form,val,index)
{
    if(index==0) v=parseFloat(val);                // N s m-2 (base)
    if(index==1) v=parseFloat(val)*0.1;            // dyn s cm-2
    if(index==2) v=parseFloat(val)*1.0e-3;         // cp
    if(index==3) v=parseFloat(val)/3600.;          // kg m-1 h-1
    if(index==4) v=parseFloat(val)*1.488164;       // lb ft-1 s-1
    if(index==5) v=parseFloat(val)*17.8579685;     // lb in-1 s-1
    form.nsm.value = ausga(form,v);
    form.dyn.value = ausga(form,v/0.1);
    form.cpo.value = ausga(form,v/1.0e-3);
    form.kgh.value = ausga(form,v*3600.);
    form.lbs.value = ausga(form,v/1.488164);
    form.lbi.value = ausga(form,v/17.8579685);
}