Cosine Partition Function

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Chef Ciel is participating an arithmetic contest now.
Why?
Because of the top prize for the contest, limited edition chopsticks.
She must calculate the values f(M, N, X) of function named cosine partition function to be the first place.
The cosine partition function f(M, N, X) is defined by
Examples are following:
f(1, 3, X) = cos(3X/3) = cos(X)
f(2, 3, X) = cos(0/3) cos(3X/3) + cos(X/3) cos(2X/3) + cos(2X/3) cos(X/3) + cos(3X/3) cos(0/3) = 2 cos(X/3) cos(2X/3) + 2 cos(X)
f(3, 1, X) = cos(0) cos(0) cos(X) + cos(0) cos(X) cos(0) + cos(X) cos(0) cos(0) = 3 cos(X)
Ciel is a great chef, however she is not good at arithmetic.
For given M, N and X, your work is calculating the value of f(M, N, X).
Input
The first line contains an integer T, the number of test cases.
Then T test cases follow.
Each test case has 2 integers M, N and a real number X.
X has at most two digits after the decimal point.
Output
For each test case, print the value of f(M, N, X).
This value must have an absolute or relative error no more than 10^{6}.
You can safely assume the magnitude of the answer is at most 10^{300}.
Constraints
1 <= T <= 50
1 <= M <= 1000000000 (10^9)
1 <= N <= 30
0 <= X <= 1
Sample Input
4 1 3 1.0 2 3 0 30 1 0.1 1 1 0.5
Sample Output
0.5403023059 4.0000000000 29.8501249583 0.8775825619
Author:  laycurse 
Tester:  anton_lunyov 
Editorial  http://discuss.codechef.com/problems/PARCOS 
Tags  laycurse march12 medium 
Date Added:  1092011 
Time Limit:  2 sec 
Source Limit:  50000 Bytes 
Languages:  ADA, ASM, BASH, BF, C, C99 strict, CAML, CLOJ, CLPS, CPP 4.3.2, CPP 4.9.2, CPP14, CS2, D, ERL, FORT, FS, GO, HASK, ICK, ICON, JAVA, JS, LISP clisp, LISP sbcl, LUA, NEM, NICE, NODEJS, PAS fpc, PAS gpc, PERL, PERL6, PHP, PIKE, PRLG, PYTH, PYTH 3.4, RUBY, SCALA, SCM guile, SCM qobi, ST, TCL, TEXT, WSPC 
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An exactly similar problem
Will be jury able to read
@aircube Yes, exponential