Simpson's Rule question, which I hate

[Hootenanny]

The question is use simpson's rule with five ordinates to find an approximation for
\int_{0}^{4} cos \left[ e^{\frac{1}{2} x} \right] dx
Here are my figures (working in radians)
y_0 = 0.540302305
y_1 = -0.077846103
y_2 = -0.911733914
y_3 = -0.228658946
y_4 = 0.448356241
Plugging these into the formula for Simpson's rule gives:
\int_{0}^{4} cos \left[ e^{\frac{1}{2} x} \right] dx \approx \frac{1}{3} \left[ (0.540302305 + 0.448356241) + 4(-0.077846103 -0.228658946) + 2(0.448356241 -0.911733914) \right]
This gives - 0.388... when the answer in the textbook is -0.6869. I know its a lot of number crunching but any help would be appreciated.

 

[becz-]

I don't really know what you are doing there..

if you just go

1/3 (y0 + 4y1 + 2y2 + 4y3 + y4) it works properly

 

[Hootenanny]

I was using the formula we have been given, you've just expanded the brackets. I've obviously just punched the numbers into my calculator wrong. Thank's.