Dot Product function errors

I can't seem to get the dot product function to work properly. When I try something like:
a = [1 2 3]
b = [4 5 6]
c = dot(a,b)

I get "Index exceeds matrix dimensions

if I try
a = [1 1 1]
c = dot (a,a)

I get

20  20  20
20  20  20
20  20  20

if I try

a = [1 2 3]
c= dot(a,a)

I get Index exceeds matrix dimensions

I've been looking at this code for an hour and can't see where it differs from the explanation of the dot produce.

Cross product works properly

Answer 1

[James Tursa]

You have inadvertently created a variable named "dot" that is shadowing the MATLAB function named "dot". Clear that variable named "dot", and in the future do not use that name anymore for variables. Similarly, don't create variables named "cross", "sum", etc. that can shadow MATLAB functions. E.g.,

>> dot = 20;
>> which dot
dot is a variable.

>> a = [1 2 3];
>> c = dot(a,a)
??? Index exceeds matrix dimensions.

>> a = [1 1 1];
>> c = dot(a,a)
c =
    20    20    20
    20    20    20
    20    20    20

>> clear dot
>> which dot
C:\Program Files (x86)\MATLAB\R2011a\toolbox\matlab\specfun\dot.m
>> c = dot(a,a)
c =
     3

[Andrew Cruce]

Thank you very much for the quick response. I'm new to MatLab and didn't realize what I had done.

Andy Cruce