fixed dependencies

vendor/gonum.org/v1/gonum/mathext/zeta.go

@@ -0,0 +1,22 @@
+// Copyright ©2016 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mathext
+
+import "gonum.org/v1/gonum/mathext/internal/cephes"
+
+// Zeta computes the Riemann zeta function of two arguments.
+//
+//	Zeta(x,q) = \sum_{k=0}^{\infty} (k+q)^{-x}
+//
+// Note that Zeta returns +Inf if x is 1 and will panic if x is less than 1,
+// q is either zero or a negative integer, or q is negative and x is not an
+// integer.
+//
+// See http://mathworld.wolfram.com/HurwitzZetaFunction.html
+// or https://en.wikipedia.org/wiki/Multiple_zeta_function#Two_parameters_case
+// for more detailed information.
+func Zeta(x, q float64) float64 {
+	return cephes.Zeta(x, q)
+}