# How to find the value before max value for vector for each 10 rows

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abdullah al-dulaimi on 29 Dec 2022
i have a vector , A=1:1:100
I want to find the values befor max values , so the result wii be, 9 19 29 39 49 59 69 79 89 99

Karim on 29 Dec 2022
Hi see below for the stept to obtain such a vector
% set up the 'max row value indicator'
n = 10
n = 10
% create array A
A = 1:100
A = 1×100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
% reshape into a matrix with a given numeber of elements:
B = reshape(A, [], n)
B = 10×10
1 11 21 31 41 51 61 71 81 91 2 12 22 32 42 52 62 72 82 92 3 13 23 33 43 53 63 73 83 93 4 14 24 34 44 54 64 74 84 94 5 15 25 35 45 55 65 75 85 95 6 16 26 36 46 56 66 76 86 96 7 17 27 37 47 57 67 77 87 97 8 18 28 38 48 58 68 78 88 98 9 19 29 39 49 59 69 79 89 99 10 20 30 40 50 60 70 80 90 100
% find the max element for each group (which in this case has 10 elements),
% but we exclude the last (i.e. 10th) elements
maxval = max(B(1:end-1,:),[],1)
maxval = 1×10
9 19 29 39 49 59 69 79 89 99
##### 2 CommentsShow NoneHide None
abdullah al-dulaimi on 29 Dec 2022
maxval =
0×100 empty double matrix? i gent this comment
abdullah al-dulaimi on 29 Dec 2022
solved, thank you

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