\begin{Schunk}
\begin{Sinput}
 abline
\end{Sinput}
\begin{Soutput}
function (a = NULL, b = NULL, h = NULL, v = NULL, reg = NULL, 
    coef = NULL, untf = FALSE, ...) 
{
    int_abline <- function(a, b, h, v, untf, col = par("col"), 
        lty = par("lty"), lwd = par("lwd"), ...) .External.graphics(C_abline, 
        a, b, h, v, untf, col, lty, lwd, ...)
    if (!is.null(reg)) {
        if (!is.null(a)) 
            warning("'a' is overridden by 'reg'")
        a <- reg
    }
    if (is.object(a) || is.list(a)) {
        p <- length(coefa <- as.vector(coef(a)))
        if (p > 2) 
            warning(gettextf("only using the first two of %d regression coefficients", 
                p), domain = NA)
        islm <- inherits(a, "lm")
        noInt <- if (islm) 
            !as.logical(attr(stats::terms(a), "intercept"))
        else p == 1
        if (noInt) {
            a <- 0
            b <- coefa[1L]
        }
        else {
            a <- coefa[1L]
            b <- if (p >= 2) 
                coefa[2L]
            else 0
        }
    }
    if (!is.null(coef)) {
        if (!is.null(a)) 
            warning("'a' and 'b' are overridden by 'coef'")
        a <- coef[1L]
        b <- coef[2L]
    }
    int_abline(a = a, b = b, h = h, v = v, untf = untf, ...)
    invisible()
}
<bytecode: 0x338ea60>
<environment: namespace:graphics>
\end{Soutput}
\end{Schunk}
