Pared-down test interpretation function

gistfile1.r

qft.interp <- function(nil, tb, mitogen, tbnil.cutoff = 0.35){

    # Set a tolerance to avoid floating point comparison troubles.
    tol <- .Machine$double.eps ^ 0.5
    
    # Set up the results vector
    result <- rep(NA, times = length(nil)) 

    # Iterate through each test.
    for(i in seq_along(result)){
        # If any test value is NA, no interpretation - skip
        if(is.na(tb[i]) | is.na(nil[i]) | is.na(mitogen[i])) {next}

        if(nil[i] + tol > 8.0) {result[i] <- "Indeterminate"} else {

            if(tb[i] - nil[i] + tol > tbnil.cutoff & tb[i] - nil[i] + tol > .25 * nil[i])
                {result[i] <- "Positive"} else {

                    if((tb[i] - nil[i] + tol < tbnil.cutoff | tb[i] - nil[i] + tol < .25 * nil[i]) &
                        !(mitogen[i] - nil[i] + tol < 0.5))
                        {result[i] <- "Negative"} else {

                            if((tb[i] - nil[i] + tol < tbnil.cutoff | tb[i] - nil[i] + tol < .25 * nil[i]) &
                                mitogen[i] - nil[i] + tol < 0.5)
                                {result[i] <- "Indeterminate"}
                }
            }
        }
    }
    return(result)
}

Primitive version of a function that's now available in the R package tbdiag