diff --git a/AUTHORS b/AUTHORS
new file mode 100644
index 00000000..eaecdf4a
--- /dev/null
+++ b/AUTHORS
@@ -0,0 +1,11 @@
+# This is the official list of gonum authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS files.
+# See the latter for an explanation.
+
+# Names should be added to this file as
+#	Name or Organization <email address>
+# The email address is not required for organizations.
+
+# Please keep the list sorted.
+
+Brendan Tracey <tracey.brendan@gmail.com>
\ No newline at end of file
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 00000000..76edf5ef
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,23 @@
+Copyright ©2013 The gonum Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the gonum project nor the names of its authors and
+      contributors may be used to endorse or promote products derived from this
+      software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
diff --git a/floats.go b/floats.go
index f31999b0..55dc16d8 100644
--- a/floats.go
+++ b/floats.go
@@ -251,14 +251,13 @@ func Nearest(s []float64, v float64) (ind int) {
 
 // NearestInSpan return the index of a hypothetical vector created
 // by Span with length n and bounds l and u whose value is closest
-// to v. Assumes u > l
-func NearestInSpan(n int, l, u float64, v float64) int {
-	if v < l {
-		return 0
-	}
-	if v > u {
-		return n - 1
+// to v. Assumes u > l. If the value is greater than u or less than
+// l, the function will panic.
+func NearestWithinSpan(n int, l, u float64, v float64) int {
+	if v < l || v > u {
+		panic("floats: value outside span bounds")
 	}
+
 	// Can't guarantee anything about exactly halfway between
 	// because of floating point weirdness
 	return int((float64(n)-1)/(u-l)*(v-l) + 0.5)
diff --git a/floats_test.go b/floats_test.go
index dddd5f1a..ede37121 100644
--- a/floats_test.go
+++ b/floats_test.go
@@ -318,32 +318,31 @@ func TestNearest(t *testing.T) {
 	}
 }
 
-func TestNearestInSpan(t *testing.T) {
-	ind := NearestInSpan(13, 7, 8.2, -1)
-	if ind != 0 {
-		t.Errorf("Wrong value when below the lower bound. %i found, %i expected", ind, 0)
+func TestNearestWithinSpan(t *testing.T) {
+
+	if !Panics(func() { NearestWithinSpan(13, 7, 8.2, 10) }) {
+		t.Errorf("Did not panic below lower bound")
 	}
-	ind = NearestInSpan(13, 7, 8.2, 9)
-	if ind != 12 {
-		t.Errorf("Wrong value when above the upper bound. %i found, %i expected", ind, 12)
+	if !Panics(func() { NearestWithinSpan(13, 7, 8.2, 10) }) {
+		t.Errorf("Did not panic above upper bound")
 	}
-	ind = NearestInSpan(13, 7, 8.2, 7.19)
+	ind := NearestWithinSpan(13, 7, 8.2, 7.19)
 	if ind != 2 {
 		t.Errorf("Wrong value when just below the bucket. %i found, %i expected", ind, 2)
 	}
-	ind = NearestInSpan(13, 7, 8.2, 7.21)
+	ind = NearestWithinSpan(13, 7, 8.2, 7.21)
 	if ind != 2 {
 		t.Errorf("Wrong value when just above the bucket. %i found, %i expected", ind, 2)
 	}
-	ind = NearestInSpan(13, 7, 8.2, 7.2)
+	ind = NearestWithinSpan(13, 7, 8.2, 7.2)
 	if ind != 2 {
 		t.Errorf("Wrong value when equal to bucket. %i found, %i expected", ind, 2)
 	}
-	ind = NearestInSpan(13, 7, 8.2, 7.151)
+	ind = NearestWithinSpan(13, 7, 8.2, 7.151)
 	if ind != 2 {
 		t.Errorf("Wrong value when just above halfway point. %i found, %i expected", ind, 2)
 	}
-	ind = NearestInSpan(13, 7, 8.2, 7.249)
+	ind = NearestWithinSpan(13, 7, 8.2, 7.249)
 	if ind != 2 {
 		t.Errorf("Wrong value when just below halfway point. %i found, %i expected", ind, 2)
 	}