# ":" (seq) bug --> patch

Martin Maechler Martin Maechler <maechler@stat.math.ethz.ch>
Tue, 3 Mar 1998 15:28:24 +0100

```I corrected the bug myself.
Here is a patch

--- seq.c.~1~	Fri Jan 16 16:07:00 1998
+++ seq.c	Tue Mar  3 15:25:27 1998
@@ -1,6 +1,6 @@
/*
- *  R : A Computer Langage for Statistical Data Analysis
- *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
+ *  R : A Computer Language for Statistical Data Analysis
+ *  Copyright (C) 1995-1998  Robert Gentleman and Ross Ihaka
*
*  This program is free software; you can redistribute it and/or modify
@@ -17,12 +17,18 @@
*  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

+/*  The `` x:y ''  primitive calls do_seq(.);
+ *
+ *  do_seq(.) calls  cross(.) if both arguments are factors
+ *	      and    seq(.)   otherwise.
+ */
+
#include "Defn.h"
#include "Mathlib.h"

static SEXP seq(SEXP call, SEXP s1, SEXP s2)
{
-	int i, n;
+	int i, n, in1;
double n1, n2;
SEXP ans;

@@ -37,28 +43,31 @@
if (ISNAN(n1) || ISNAN(n2))
errorcall(call, "NA/NaN argument\n");

-	if (n1 <= INT_MIN || n2 <= INT_MIN || n1 > INT_MAX || n2 > INT_MAX)
+	if (n1 <= INT_MIN || n2 <= INT_MIN || n1 > INT_MAX || n2 > INT_MAX
+	    || abs(n2 - n1) >= INT_MAX)
errorcall(call, "argument too large in magnitude\n");

-	if (n1 <= n2) {
-		n = n2 - n1 + 1 + FLT_EPSILON;
-		ans = allocVector(INTSXP, n);
-		for (i = 0; i < n; i++)
-			INTEGER(ans)[i] = n1 + i;
-	}
-	else {
-		n = n1 - n2 + 1 + FLT_EPSILON;
+	n = abs(n2 - n1) + 1 + FLT_EPSILON;
+	if (n1 == (in1 = (int)(n1))) {
ans = allocVector(INTSXP, n);
-		for (i = 0; i < n; i++)
-			INTEGER(ans)[i] = n1 - i;
+		if (n1 <= n2)
+			for (i = 0; i < n; i++) INTEGER(ans)[i] = in1 + i;
+		else
+			for (i = 0; i < n; i++) INTEGER(ans)[i] = in1 - i;
+	} else {
+		ans = allocVector(REALSXP, n);
+		if (n1 <= n2)
+			for (i = 0; i < n; i++) REAL(ans)[i] = n1 + i;
+		else
+			for (i = 0; i < n; i++) REAL(ans)[i] = n1 - i;
}
return ans;
}

/*  cross  -  the "cross" of two factors  */

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
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```