Error using + Matrix dimensions must agree.

This function implements Boyer moore string matching algorithm. It gives me the following error message at line 19 (start_pos = start_pos + lookup_table(last_Char));

Both start_pos and the index i am looking in lookup_table is 1 * 1 based so i dont get where matrix size mismatch? Can anyone help me with this ??

Error using  + 
Matrix dimensions must agree.

Error in boyer (line 19)
    start_pos = start_pos +
    lookup_table(last_char);

function [final_count] = boyer(haystack, needle, nlength, start_pos, end_pos )
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here

temp_count = 0;
final_count = 0;
offset = nlength;

lookup_table = createTable(needle, nlength);

while(start_pos <= end_pos - nlength + 1)

      last_char = haystack(start_pos + nlength - 1);

      if(last_char == needle(nlength) & strncmpi(haystack(1,start_pos:end_pos), needle, nlength - 1) == 1)
          temp_count = temp_count + 1;
      end

      start_pos = start_pos + lookup_table(last_char);
  end

final_count = final_count + temp_count;

end

[dpb]

Need to see what lookup_table looks like--looks as though it somehow isn't what you think it is.

[Walter Roberson]

I think some of those must be functions.

[Vignesh]

@dcpb Lookup_table is a table of 255 characters i.e.size (1*255) where i denote a value to the characters of my pattern. If the char in the pattern doesnt match the char in the text, it looks in the table and for corresponding value of char it jumps that many positions. Below is the lookup_table function.

function [lookup_table] = createTable(needle, nlength)

%UNTITLED4 Summary of this function goes here % Detailed explanation goes here % pre-allocating storage for the look up table

UCHAR_MAX = 255; bad_char_skip_table = zeros(1, UCHAR_MAX); bad_char_skip_table(1, 1:UCHAR_MAX) = nlength;

if nlength >= 1 for i = (1: nlength - 1) bad_char_skip_table(needle(i)) = nlength - i; end end lookup_table = bad_char_skip_table;

end

[dpb]

Need to format your code so it's legible...simplest I've found is to just type two spaces at the beginning of a line starting a new paragraph. Keep at it until it looks right in the preview window.

Probably the easiest way for you to find the problem is to use the debugger and when you reach the error point and stop look at the size() of the various terms to see who's the actual culprit. One thought I can't tell easily w/ the unformatted code and little context is is it possible lookup_table ever returns []?

[the cyclist]

Ideally, give us the smallest possible self-contained code that we can run. This makes debugging much faster for us. It is also quite common to discover the error yourself, in the process of making that small amount of code.