function uv(){fh=document.forms[0];def();ur()}

function ur(){fh=document.forms[0];rr1=fh.r1.value;rr2=fh.r2.value;rqs=fh.reqs.value=rr1-(-1)*rr2;rq=fh.req.value=1/(1/rr1-(-1)*1/rr2);ii=fh.i.value=fh.vb.value/rq;iiis=fh.iis.value=fh.vb.value/rqs;fh.i1.value=fh.vb.value/rr1;fh.i2.value=fh.vb.value/rr2;fh.v1.value=iiis*rr1;fh.v2.value=iiis*rr2}

function ur2(){fh=document.forms[0];rr1=fh.r1.value;rr2=fh.r2.value;rqs=fh.reqs.value=rr1-(-1)*rr2;rq=fh.req.value=1/(1/rr1-(-1)*1/rr2);ii=fh.i.value;vvb=fh.vb.value=ii*rq;iiis=fh.iis.value=fh.vb.value/rqs;fh.i1.value=fh.vb.value/rr1;fh.i2.value=fh.vb.value/rr2;fh.v1.value=iiis*rr1;fh.v2.value=iiis*rr2}

function ur3(){fh=document.forms[0];rr1=fh.r1.value;rr2=fh.r2.value;rqs=fh.reqs.value=rr1-(-1)*rr2;rq=fh.req.value=1/(1/rr1-(-1)*1/rr2);iiis=fh.iis.value;fh.vb.value=iiis*rqs;ii=fh.i.value=fh.vb.value/rq;fh.i1.value=fh.vb.value/rr1;fh.i2.value=fh.vb.value/rr2;fh.v1.value=iiis*rr1;fh.v2.value=iiis*rr2}


<!--default values are set for parameters which have zero values-->
<!--There is value in having an overall default function for a calculation to provide values for all parameter which you dont want to default to zero-->
function def(){fh=document.forms[0];if (fh.r1.value==0)fh.r1.value=1;if (fh.r2.value==0)fh.r2.value=1}