Exercise: work from tabulated data

Computing work by integrating F(x)cos(alpha(x)) from a table, using trapezoid, Simpson and midpoint.

Integrating a table

ExampleWork W

With step 1.52 and data F=[0,40.04,57.83,62.28,46.71,53.38,22.24], alpha=[0.5,1.4,0.75,0.9,1.3,1.48,1.5], compute W=∫F(x)cos(alpha(x))dx.

  1. First build the tabulated integrand by multiplying F by cos(alpha):

    gi=Ficos(αi)g_i=F_i\cos(\alpha_i)
  2. Applying trapezoid and Simpson to the measured data gives:

    T=161.0507484870318,S=158.3980289247424T=161.0507484870318,\qquad S=158.3980289247424
  3. For midpoint, interpret the data as central heights and use auxiliary nodes of step 1.52/2:

    M=162.24638M=162.24638

The rule must match the meaning of the table: in midpoint, the measured values are rectangle centres, not endpoints.