R/H.Earth.solar.R

In widals: Weighting by Inverse Distance with Adaptive Least Squares

H.Earth.solar <-
function(x, y,  dateDate) { ######################
    Hst.ls <- list()
    n <- length(y)
    tau <- length(dateDate)
    equinox <- strptime( "20110320", "%Y%m%d" )
    for(i in 1:tau) {
        this.date <- dateDate[i]
        dfe <- as.integer( difftime(this.date, equinox, units="day")) ; dfe
        psi <- 23.5 * sin( 2*pi*dfe/365.25 ) ; psi
        
        eta <- 90 - (360/(2*pi)) * acos(  cos(2*pi*y/360) * cos(2*pi*psi/360) +  sin(2*pi*y/360) * sin(2*pi*psi/360) )
        surface.area <- sin(2*pi*eta/360) ; surface.area
        #	surface.area[ surface.area < 0 ] <- 0
        Hst.ls[[i]] <- cbind( surface.area )
    }
    return(Hst.ls)
}