Double integration with respect to same variable

Hi,

I'm trying to integrate experimental data twice with respect to the same variable, and then implement it in indefinite equations that include the integration constants. I've defined x2 as my integration variable, and A and B are the respective integration constants as if this were an indefinite integral.

Here is some of my scratch work on the equations I'm using, and how I've setup the integration equations with the appropriate boundary conditions to solve for A and B.

Here is the code I have currently, but with a comparison to simulation results, the values are overpredicting. I know this is an involved problem, but if anyone has any insight, it'd be very much appreciated. Thanks!

x2 = x(icg + 1: iff);
x2 = x2 - x2(1);

I2 = I(icg + 1: iff);
xf2 = x_f - x_cg;
M2 = F*(xf2 - x2);
f2 = M2./(E.*I2);

[X] = meshgrid(x2,x2);
M2 = F*(xf2 - X);
ieq = M2./(E.*I2);

int1 = trapz(x2,f2);
int2 = trapz(x2,trapz(x2,ieq,2));

A = int1;
B = int2;

w(1,icg + 1:iff) = -int2 + B + (A*x2);