Index in position 1 is invalid. Array indices must be positive integers or logical values.

I have :

c(i,2) = 272.0000
c(i,1) = 42.0000
and L(272.0000,42.0000) gives  2

but when I do

L( c(i,2), c(i,1) ) 

(L is a 697x103 double)

I got

Index in position 1 is invalid. Array indices must be positive integers or logical values.

Answer 1

[Dyuman Joshi]

The error occurs because your data is not exactly an integer even though it might look like it.

%Data displayed in the default format i.e. short format
y = 1.0000123

y = 1.0000

Type

format long

in your code and see the value of the the elements.

y

y = 
   1.000012300000000

Use round(), floor() or ceil() according to what you want to do.

L( round(c(i,2)), round(c(i,1)))

[Xavier]

Thank you very much for your answer, I tried with floor() and it works. It is quite surprising though because the value in c are from the use of ginput() so I thought it gives integers corresponding to a pixel.

Answer 2

[Mathieu NOE]

hello

depending of your format, the command window will display more or less decimals

I suspect

c(i,2) = 272.0000...............123

c(i,1) = 42.0000...............789

are not 100% integer so you have to round them to the nearest integer to make your code work

L( round(c(i,2)), round(c(i,1)) ) should now display the correct value

[Xavier]

Hello, thank you very much for your answer. You find the issue and it works now. Thank you !