Added derivative and Hessian for Picheny test function

Author: stefan-k

crates/argmin-testfunctions/proptest-regressions/picheny.txt

@@ -0,0 +1,9 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 5aa3ba0e4323a8dc0dd12ac1dbc1c38b376037a0c0bb90ccc29c39d7eaf085b0 # shrinks to a = 0.0, b = 0.0
+cc eee01c0df03e5b5723d2865397ab5db4834e8bd8e0e97a6bc9cc8788d26edbdf # shrinks to a = 0.8734667101799871, b = 0.5043381978510337
+cc 99447ad3249d3b6b719ee686fbd85095e8488bfd0e433c56571eadf8539bff21 # shrinks to a = 0.5555316208817483, b = 0.15793555431430475