diff -r 172527f61bd3 seq.c
--- a/seq.c	Mon Apr 16 21:48:50 2012 +0200
+++ b/seq.c	Mon Apr 16 18:27:13 2012 -0500
@@ -5,7 +5,6 @@
 #include <unistd.h>
 #include <stdbool.h>
 #include <libgen.h>
-#include <regex.h>
 
 #include "util.h"
 
@@ -30,12 +29,12 @@
 	char *exp;
 	int shift;
 
-	if (d[0] == '-' || d[0] == '+')
+	if (d[0] == '+')
 		d++;
 	exp = strpbrk(d, "eE");
 	shift = exp? atoi(exp+1) : 0;
 
-	return MAX(0, strspn(d, "0123456789")+shift);
+	return MAX(0, strspn(d, "-0123456789")+shift);
 }
 
 int
@@ -44,8 +43,6 @@
 	char *exp;
 	int shift, after;
 
-	if (d[0] == '-' || d[0] == '+')
-		d++;
 	exp = strpbrk(d, "eE");
 	shift = exp ? atoi(exp+1) : 0;
 	after = (d = strchr(d, '.'))? strspn(d+1, "0123456789") : 0;
@@ -56,15 +53,29 @@
 int
 validfmt(char *fmt)
 {
-	regex_t reg;
-	int ret;
-
-	regcomp(&reg, "\\([^%]|%%\\)*%[0-9]*\\.[0-9]*[fFgG]"
-			"\\([^%]|%%\\)*", REG_NOSUB);
-	ret = regexec(&reg, fmt, 0, NULL, 0);
-	regfree(&reg);
-
-	return (ret == 0);
+	int end = 0;
+NonFormat:
+	while(*fmt)
+		if(*fmt++=='%')
+			goto Format;
+	return 1;
+Format:
+	if(*fmt=='%'){
+		fmt++; 
+		goto NonFormat;
+	}
+	if(end)
+		return 0;
+	if(strchr(" +-", *fmt))
+		fmt++;
+	fmt+=strspn(fmt, "0123456789");
+	if(*fmt == '.')
+		fmt++;
+	fmt+=strspn(fmt, "0123456789");
+	if(!strchr("fFgGeE", *fmt))
+		return 0;
+	end = 1;
+	goto NonFormat;
 }
 
 int
@@ -72,7 +83,7 @@
 {
 	char c, *fmt, ftmp[4096], *sep, *starts, *steps, *ends;
 	bool wflag, fflag;
-	double start, step, end, out;
+	double start, step, end, out, dir;
 	int left, right;
 
 	sep = "\n";
@@ -101,7 +112,6 @@
 			break;
 		}
 	}
-
 	if (wflag && fflag)
 		eprintf("-f and -w cannot be combined.\n");
 
@@ -134,21 +144,14 @@
 	start = atof(starts);
 	step = atof(steps);
 	end = atof(ends);
+	dir = (step>0)?1.0:-1.0;
 
 	if (step == 0)
 		return EXIT_FAILURE;
+	if (start*dir > end*dir)
+		return EXIT_FAILURE;
 
-	if (start > end) {
-		if (step > 0)
-			return EXIT_FAILURE;
-	} else if (start < end) {
-		if (step < 0)
-			return EXIT_FAILURE;
-	}
-
-	right = MAX(digitsright(starts),
-			MAX(digitsright(ends),
-				digitsright(steps)));
+	right = MAX(digitsright(starts), digitsright(steps));
 	if (wflag) {
 		left = MAX(digitsleft(starts), digitsleft(ends));
 
@@ -161,23 +164,11 @@
 
 	for (out = start;;) {
 		printf(fmt, out);
-
 		out += step;
-		if (start > end) {
-			if (out >= end) {
-				printf("%s", sep);
-			} else {
-				break;
-			}
-		} else if (start < end) {
-			if (out <= end) {
-				printf("%s", sep);
-			} else {
-				break;
-			}
-		} else {
+		if(out*dir <= end*dir)
+			printf("%s", sep);
+		else 
 			break;
-		}
 	}
 	printf("\n");