# Homework Help: MATLAB help

1. Jan 19, 2010

### henryc09

1. The problem statement, all variables and given/known data
A modified form of the trapezium rule for calculating the area under a curve makes use of strips
of varying width: by using narrower strips where the gradient varies more rapidly, better
accuracy can be achieved. Create a function to perform the integral

$$\int1/x dx$$ between 1 and 101

using the trapezium rule with strips that increase geometrically in width, such that,

$$\Delta$$Xn=rn-1$$\Delta$$X1 where $$\Delta$$Xn is the width of the nth strip and r is a constant (which is an
input to the function).
Choose the value of Δx1 to give a total of 100 strips for any value of r (hint: you will need the
formula for the sum of a geometric progression to calculate Δx1).

2. Relevant equations

3. The attempt at a solution

Not sure where to start really, I mean a simple application of the trapezium rule to it would be simple enough. Define a vector x=[1:1:101] and then y=1./x and integral=trapz(x,y) or something along those lines (I don't have access to MATLAB from home so I couldn't be sure). Any point in the right direction would be much appreciated.

Last edited: Jan 19, 2010
2. Dec 25, 2010

### mangofun12

Did you ever find an answer to this question?