function compute(form)
{
var conc=0
var c=0
concen=(eval(form.c.value))
lcalc=Math.log(concen)
phcalc=-lcalc/2.302585
form.conc.value=phcalc
form.edita.value="(-log" +form.c.value +")"
}
function clearForm(form)
{
	form.c.value="0";
	form.conc.value="";
	form.edita.value="";
}