remove from fRegress.R and fRegress.numeric.R and put it its own file

Author: sbgraves237

R/eigchk.R

@@ -0,0 +1,22 @@
+eigchk <- function(Cmat) {
+  
+  #  check Cmat for singularity
+  
+  eigval <- eigen(Cmat)$values
+  ncoef  <- length(eigval)
+  if (eigval[ncoef] < 0) {
+    neig <- min(length(eigval),10)
+    cat("\nSmallest eigenvalues:\n")
+    print(eigval[(ncoef-neig+1):ncoef])
+    cat("\nLargest  eigenvalues:\n")
+    print(eigval[1:neig])
+    stop("Negative eigenvalue of coefficient matrix.")
+  }
+  if (eigval[ncoef] == 0) stop("Zero eigenvalue of coefficient matrix.")
+  logcondition <- log10(eigval[1]) - log10(eigval[ncoef])
+  if (logcondition > 12) {
+    warning("Near singularity in coefficient matrix.")
+    cat(paste("\nLog10 Eigenvalues range from\n",
+              log10(eigval[ncoef])," to ",log10(eigval[1]),"\n"))
+  }
+}