The at_con and at_var functions retrieve a sub-MC from an MC. What follows is an extended example of at_con's use; at_var is used the same way. Output came from view_k, but some white space was subsequently inserted to make the numbers easier to read.

The number inside the angle brackets indicates the order of the desired sub-MC. Because this number is a C++ template parameter, it must be known at compile time.

The number inside the parentheses indicates which of the sub-MC's of that order to select. This can be an ordinary variable not known until run time.

 --------- given this definition --------- 

mcd5 const x      {{{{{5.00,5.01},{5.02,5.03}},{{5.04,5.05},{5.06,5.07}}},
                    {{{5.08,5.09},{5.10,5.11}},{{5.12,5.13},{5.14,5.15}}}},
                   {{{{5.16,5.17},{5.18,5.19}},{{5.20,5.21},{5.22,5.23}}},
                    {{{5.24,5.25},{5.26,5.27}},{{5.28,5.29},{5.30,5.31}}}}};

 --------- then all the sub-MC's are --------- 
 
 x.at_con<5>( 0): [[[[[5.00 5.01] [5.02 5.03]] [[5.04 5.05] [5.06 5.07]]]
                    [[[5.08 5.09] [5.10 5.11]] [[5.12 5.13] [5.14 5.15]]]]
                   [[[[5.16 5.17] [5.18 5.19]] [[5.20 5.21] [5.22 5.23]]]
                    [[[5.24 5.25] [5.26 5.27]] [[5.28 5.29] [5.30 5.31]]]]]
 
 x.at_con<4>( 0):  [[[[5.00 5.01] [5.02 5.03]] [[5.04 5.05] [5.06 5.07]]]
                    [[[5.08 5.09] [5.10 5.11]] [[5.12 5.13] [5.14 5.15]]]]
 x.at_con<4>( 1):  [[[[5.16 5.17] [5.18 5.19]] [[5.20 5.21] [5.22 5.23]]]
                    [[[5.24 5.25] [5.26 5.27]] [[5.28 5.29] [5.30 5.31]]]]
 
 x.at_con<3>( 0):   [[[5.00 5.01] [5.02 5.03]] [[5.04 5.05] [5.06 5.07]]]
 x.at_con<3>( 1):   [[[5.08 5.09] [5.10 5.11]] [[5.12 5.13] [5.14 5.15]]]
 x.at_con<3>( 2):   [[[5.16 5.17] [5.18 5.19]] [[5.20 5.21] [5.22 5.23]]]
 x.at_con<3>( 3):   [[[5.24 5.25] [5.26 5.27]] [[5.28 5.29] [5.30 5.31]]]
 
 x.at_con<2>( 0):    [[5.00 5.01] [5.02 5.03]]
 x.at_con<2>( 1):    [[5.04 5.05] [5.06 5.07]]
 x.at_con<2>( 2):    [[5.08 5.09] [5.10 5.11]]
 x.at_con<2>( 3):    [[5.12 5.13] [5.14 5.15]]
 x.at_con<2>( 4):    [[5.16 5.17] [5.18 5.19]]
 x.at_con<2>( 5):    [[5.20 5.21] [5.22 5.23]]
 x.at_con<2>( 6):    [[5.24 5.25] [5.26 5.27]]
 x.at_con<2>( 7):    [[5.28 5.29] [5.30 5.31]]
 
 x.at_con<1>( 0):     [5.00 5.01]
 x.at_con<1>( 1):     [5.02 5.03]
 x.at_con<1>( 2):     [5.04 5.05]
 x.at_con<1>( 3):     [5.06 5.07]
 x.at_con<1>( 4):     [5.08 5.09]
 x.at_con<1>( 5):     [5.10 5.11]
 x.at_con<1>( 6):     [5.12 5.13]
 x.at_con<1>( 7):     [5.14 5.15]
 x.at_con<1>( 8):     [5.16 5.17]
 x.at_con<1>( 9):     [5.18 5.19]
 x.at_con<1>(10):     [5.20 5.21]
 x.at_con<1>(11):     [5.22 5.23]
 x.at_con<1>(12):     [5.24 5.25]
 x.at_con<1>(13):     [5.26 5.27]
 x.at_con<1>(14):     [5.28 5.29]
 x.at_con<1>(15):     [5.30 5.31]
 
 x.at_con<0>( 0):      5.00
 x.at_con<0>( 1):      5.01
 x.at_con<0>( 2):      5.02
 x.at_con<0>( 3):      5.03
 x.at_con<0>( 4):      5.04
 x.at_con<0>( 5):      5.05
 x.at_con<0>( 6):      5.06
 x.at_con<0>( 7):      5.07
 x.at_con<0>( 8):      5.08
 x.at_con<0>( 9):      5.09
 x.at_con<0>(10):      5.10
 x.at_con<0>(11):      5.11
 x.at_con<0>(12):      5.12
 x.at_con<0>(13):      5.13
 x.at_con<0>(14):      5.14
 x.at_con<0>(15):      5.15
 x.at_con<0>(16):      5.16
 x.at_con<0>(17):      5.17
 x.at_con<0>(18):      5.18
 x.at_con<0>(19):      5.19
 x.at_con<0>(20):      5.20
 x.at_con<0>(21):      5.21
 x.at_con<0>(22):      5.22
 x.at_con<0>(23):      5.23
 x.at_con<0>(24):      5.24
 x.at_con<0>(25):      5.25
 x.at_con<0>(26):      5.26
 x.at_con<0>(27):      5.27
 x.at_con<0>(28):      5.28
 x.at_con<0>(29):      5.29
 x.at_con<0>(30):      5.30
 x.at_con<0>(31):      5.31