From d52e522a9abea09fae1189b066e2a2e1dbb9cb34 Mon Sep 17 00:00:00 2001
From: Johannes Ranke <johannes.ranke@jrwb.de>
Date: Fri, 14 Sep 2018 14:06:57 +0200
Subject: Avoid nls crashes by checking for a correlation first

---
 R/mkinfit.R | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/R/mkinfit.R b/R/mkinfit.R
index ecbef67e..2c4e3268 100644
--- a/R/mkinfit.R
+++ b/R/mkinfit.R
@@ -415,6 +415,13 @@ mkinfit <- function(mkinmod, observed,
         # We need unweighted residuals to update the weighting
         cost_tmp <- cost(fit$par)
 
+        p_tmp <- cor.test(abs(cost_tmp$residuals$res.unweighted),
+                          cost_tmp$residuals$obs, method = "kendall")$p.value
+        if (p_tmp > 0.1) {
+          stop("No correlation of absolute residuals with observed values found.\n",
+               "Try without reweighting or with reweight.method = 'obs'.")
+        }
+
         tc_fit <- try(
           nls(abs(res.unweighted) ~ sigma_twocomp(obs, sigma_low, rsd_high),
             start = list(sigma_low = tc["sigma_low"], rsd_high = tc["rsd_high"]),
-- 
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