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

Hello,

I have tried various combinations of integers and no matter what I seem to do my code won't work.

inkvar=length(changeink)*var(rat_ink(changeink));

I have tried several different combinations including but not limited too:

inkvar=length(changeink)*var(rat_ink(changeink,1),1));
ink_variance=length(changeink)*var(rat_ink(changeink(1,1)*1,2));

I have even tried changing the names of my variables, nothing is working! I don't know what else to do!

changeink is 10x1 and rat_ink is 10x2

[Xingwang Yong]

It seems changeink contains negative integer.

[Walter Roberson]

What is min(changeink) and max(changeink) ?

What shows up for

unique(mod(changeink,1))

[MacKenzie King]

There are no negative integers in changeink:

79.7000000000000

72.8000000000000

67.0000000000000

68.8000000000000

65.5000000000000

70.3000000000000

77.7000000000000

88.4000000000000

76.8000000000000

72

unique(mod(changeink,1))

ans =

0

0.3000

0.4000

0.5000

0.7000

0.7000

0.8000

0.8000

1.0000

min(changeink)

ans =

65.5000

max(changeink)

ans =

88.4000

Answer 1

[Cris LaPierre]

Your values are not integers. For example, what value should rat_ink(79.7,1) return? Valid indices are 1, 2, 3, etc.

[MacKenzie King]

What does this mean? How do I make them integers?

[Cris LaPierre]

It means that MATLAB does not how to index the 77.9th row. There is a 77th row, and a 78th row, but nothing inbetween.

Integers do not contain decimal values. They are whole numbers. You can make a decimal value an integer using round, ceil, floor, or fix for example. You should probably do a little reading about each one to determine which is best for you.

[MacKenzie King]

I rounded everything but it is still giving me the same error message.

[Cris LaPierre]

You use indices inside indices. I suspect the same thing is going on with rat_ink.

Try the following:

rat_ink(round(changeink),1),1)
var(rat_ink(round(changeink),1),1))
var(round(rat_ink(round(changeink),1)),1))