MATLAB: Integration within particular range

definite integralnumerical integration

Dear All,

I want to integrate the x, y. I use trapz(x,y). It gives me 1000. X-range id 0 to 4.45. But how to integrate with upper limit and lower limit i.e. 2 to 3. How to do it ? x is the first column and y is the 2nd column of the attached excel sheet.

Best Answer

idx = x>=2 && x<=3;
xp = x(idx);
yp = y(idx);
value = trapz(xp,yp)

Related Solutions

MATLAB: Finite Integral with periodic values of x

idx = (x>=0.3 & x<=4.5);
xp = x(idx);
yp = y(idx);
F = cumtrapz(xp,yp);
F = F(end) - F;
plot(xp,F)

MATLAB: Numerical integration

This turned out to be surprisingly tricky, but here is the solution. First, define a function

function fzv = integrateOverSecondPair(fun,x,y,zmin,zmax,vmin,vmax)
% DBLQUAD evaluates FUN for a vector x and scalar y. The backwards loop is
% Matt Fig's dynamic preallocation.
for ii=numel(x):-1:1
  g = @(z,v) fun(x(ii),y,z,v);
  fzv(ii) = dblquad(g,zmin,zmax,vmin,vmax);
end

Then use the commands

fzv = @(x,y) integrateOverSecondPair(@f,x,y,zmin,zmax,vmin,vmax);
fxyzv = dblquad(fzv,xmin,xmax,ymin,ymax);

Best Answer

Related Solutions

MATLAB: Finite Integral with periodic values of x

MATLAB: Numerical integration

Related Question