STK_TESTFUN_TWOBUMPS computes the TwoBumps response function
CALL: Z = stk_testfun_twobumps (X)
computes the response Z of the TwoBumps function at X.
The TwoBumps function is defined as:
TwoBumps(x) = - (0.7x + sin(5x + 1) + 0.1 sin(10x))
for x in [-1.0; 1.0].
Package: stk