18/09/16 21:14:22.32 MIF83oNx.net
# The ambulance arrives X hours ealier at hospital,
# when the patient leave clinic s hours earlier than planned
# and encounter the ambulance t hours later,
# ambulance runs with the velocity of v0 without patient, and v1 with patient
# clinic car runs with the velocity of w
Earlier <- # s hour earlier departure, X hour earlier arrival
function(s=NULL,X=NULL,t=NULL,v0=60,v1=45,w=30){
if(is.null(s)) re=c(s=X/(v0/(v0+w)*w*(1/v0+1/v1)),t=X/w/(1/v0+1/v1))
if(is.null(X)) re=c(X=s*v0/(v0+w)*w*(1/v0+1/v1),t=s*v0/(v0+w))
if(!is.null(t)) re=c(s=t + t*w/v0, X = t*w*(1/v0+1/v1))
return(re)
}
Earlier(X=10/60)*60
Earlier(s=30/60)*60
Earlier(t=30/60)*60