want to see what this flop-count stuff is...
>> help flops

 FLOPS Floating point operation count.
    FLOPS returns the cumulative number of floating point operations. 
 
    FLOPS(0) resets the count to zero.
 
    It is not feasible to count absolutely all floating point
    operations, but most of the important ones are counted.
    Additions and subtractions are one flop if real and two if
    complex. Multiplications and divisions count one flop each
    if the result is real and six flops if it is not.
    Elementary functions count one if real and more if complex.
 
    Some examples. If A and B are real N-by-N matrices, then
       A + B     counts N^2 flops,
       A * B     counts 2*N^3 flops,
       LU(A)     counts roughly (2/3)*N^3 flops.
       A ^ P     counts 2*C*N^3 flops where, for integer P and
                 D = DEC2BIN(P), C = length(D)+sum(D=='1')-1.

set the flop counter to zero
>> flops(0);
>> 2 + 3
ans =
     5

how many flops have happened:
>> flops
ans =
     1

do some more operations and check again
>> for i=1:100; 2+3; end
>> flops
ans =
   101

reset flop counter and check it's reset.  Then see how many flops a 
trig function counts for.  
>> flops(0);
>> flops
ans =
     0

>> cos(1);
>> flops
ans =
     1

how does cputime work?
>> help cputime

 CPUTIME CPU time in seconds.
    CPUTIME returns the CPU time in seconds that has been used
    by the MATLAB process since MATLAB started.  
 
    For example:
 
        t=cputime; your_operation; cputime-t
 
    returns the cpu time used to run your_operation.            
  
    The return value may overflow the internal representation
    and wrap around.
 
    See also ETIME, TIC, TOC, CLOCK

first set t to be the current cputime, then do some work, and find
the elapsed cputime by taking the difference between the current
cputime and the original cputime.
>> t = cputime
>> t =
     0

>> A = inv(rand(100,100));
>> t = cputime-t
t =
   44.3800

how does tic, toc work?
>> help tic

 TIC Start a stopwatch timer.
    The sequence of commands
        TIC, operation, TOC
    prints the number of seconds required for the operation.
 
    See also TOC, CLOCK, ETIME, CPUTIME.

>> tic; A = inv(rand(200,200)); toc
elapsed_time =
    0.8800

>> tic; A = inv(rand(300,300)); toc
elapsed_time =
    3.4000

compare the flop counts for evaluating a 100th degree polynomial in a
direct manner, versus evaluating it in a clever manner.
>> n = 100; 2*n/60, (n^2/2 + 3*n/2)/60
ans =
    3.3333
ans =
   85.8333

compare the flop counts for evaluating a 1000th degree polynomial in a
direct manner, versus evaluating it in a clever manner.  We then
convert the longer time in tominutes and then into hours
>> n = 1000; 2*n/60, (n^2/2 + 3*n/2)/60
ans =
   33.3333
ans =
  8.3583e+003

>> ans/60
ans =
  139.3056
>> ans/60
ans =
    2.3218

>> diary off