near: fix for negative inputs (SF#3092250)

The formula used for 'within a factor of' was only correct for
positive numbers.

src/hal/components/near.comp

@@ -1,14 +1,23 @@
 component near "Determine whether two values are roughly equal.";
-pin in float in1;
-pin in float in2;
+pin in float in1_;
+pin in float in2_;
 param rw float scale=1;
 param rw float difference=0;
-pin out bit out "true if in1/scale <= in2 <= in1*scale, OR |in1-in2| <= difference";
+pin out bit out """
+\\fBout\\fR is true if \\fBin1\\fR and \\fBin2\\fR are within a factor of
+\\fBscale\\fR (i.e., for in1 positive, in1/scale <= in2 <= in1*scale), OR
+if their absolute difference is no greater than \\fBdifference\\fR (i.e.,
+|in1-in2| <= difference).  \\fBout\\fR is false otherwise.""";
 function _;
 license "GPL";
 ;;
 #include "rtapi_math.h"
 FUNCTION(_) {
+	double in1 = in1_, in2 = in2_;
+	if(in1 < 0) {
+		in1 = -in1;
+		in2 = -in2;
+	}
 	if((scale > 1 && in1/scale <= in2 && in2 <= in1*scale) || fabs(in1-in2) <= difference)
 		out = 1;
 	else