excel x & y

Hi there i read two columns from an excel file. first column is x and second is y. i get x from user , how can a i find y for that x?

for example user inputs 0.531 i must show 0.5103 or user inputs 0.536 i must show 0.5154

my matrix is 2x1000 ( 2 columns and 1000 rows) please help

Answer 1

[Azzi Abdelmalek]

If M is your matrix

M=[0.5310 0.5103;0.5320 .5080;0.5330 0.5144]
x=0.5310
idx=ismember(M(:,1),x)
y=M(idx,2)

[Alireza Lashgary]

thanks