dilevin/csc417-a1-mass-spring-1d

Assignment 1 on one-dimensional mass spring systems for CSC2549, at the University of Toronto

csc417-a1-mass-spring-1d's Issues

Typo in posted recording lecture

I believe there is a v_t on the right hand side for the bottom-left equation?

why there is an extra parameter qdot?

Hi, can someone explain why there is an extra parameter qdot? Thank a lot!

glfwWindowShouldClose: Assertion `window != NULL' failed.

I tried to compile the starter code on teach.cs through a remote login and got this error.

I was using the NX client to login remotely. Did anybody else get something similar? I am also taking CSC419 and this happens when I compile their starter code for the first assignment, so it might have to do with using the libigl library through a remote connection (or it could just be my computer).

Thanks!

check answer with classmate

Are we allowed to compare the simulation results (Eg recording the libigl window, sharing the .exe+.ilk+.pdb files made by command line) with classmates?

show face labels crashes

Hey, Not sure if we need this at all but playing around with the UI I noticed selecting show faces labels crashes it. See below:

This was output in shell:

Assertion failed: draw_list->_VtxCurrentIdx < (1 << 16) && "Too many vertices in ImDrawList using 16-bit indices. Read comment above", file C:\Users\sabba\source\repos\csc417_a1\extern\libigl\external\imgui\imgui.cpp, line 3725

Are we writing our own force function for each of the four methods?

If so, I don't know how to compute the force by using only the coordinate and the velocity. Is there any hint?

Testing

Anyone have advice on testing our time integrations other than comparing the phase graphs?

[Clarification] Input for force and stiffness in the four integrations

Sorry that the function handle force and stiffness should take 3 variables as input instead:

force(f, q, qdot) - a function that computes the force acting on the mass as a function. This takes q and qdot as input parameters. f is the output force.
stiffness(k, q, qdot) - a function that computes the stiffness (negative second derivative of the potential energy). This takes q and qdot as input parameters. k is the output stiffness.

CMake Error on Windows

Hey,

I'm seeing this error on build:

Is there anything I can do about this or should I go chase a linux subsystem?

Thanks,

Missing headers on stock Ubuntu 18.04 with nvidia drivers 430.50

This isn't an issue - rather help for others seeking to do a debug build on a stock install of Ubuntu 18.04 with nvidia drivers. You have to make sure the OpenGL header files are installed as well as a handfull of other dependencies or you cmake with -DCMAKE_BUILD_TYPE=Debug will fail. I imagine if you use the CDF machines, this is a non-issue as all the packages are most likely installed there.

Those packages are:
mesa-comon-dev
libgl1-mesa-dev
libglu1-mesa-dev
x11proto-dev
libxrandr-dev
libxinerama-dev
libxcursor-dev
libxi-dev

Submission format

Hello! On MarkUs, there's a list of required files:

Should we submit only these files, or the whole project in the MarkUs repo? Just want to know so I can submit the preferred way now and going forward. Thanks in advance!

Cant pass Rvalue reference to force or stiffness

You can't pass R-Type references to the force or stiffness functions unless q and qdot are constants. This issue means that you cant use some features of Eigen.
To fix it you have to change

auto force = [](Eigen::VectorXd &f, Eigen::VectorXd &q, Eigen::VectorXd &qdot) { dV_spring_particle_particle_dq(f, q, stiffness); f *= -1; };
auto stiff = [](Eigen::MatrixXd &k, Eigen::VectorXd &q, Eigen::VectorXd &qdot) { d2V_spring_particle_particle_dq2(k, q, stiffness); k *= -1; };

to

auto force = [](Eigen::VectorXd &f, const Eigen::VectorXd &q, const Eigen::VectorXd &qdot) { dV_spring_particle_particle_dq(f, q, stiffness); f *= -1; };
auto stiff = [](Eigen::MatrixXd &k, const Eigen::VectorXd &q, const Eigen::VectorXd &qdot) { d2V_spring_particle_particle_dq2(k, q, stiffness); k *= -1; };

Lets leave issues open at least until the "suggested" assignment due date.

It will make it easier for other people to find solutions to common problems.

Helpful resources

I'm not sure if I should have opened an issue on the main course page, but since these are specific to A1, I'll leave them here:

• Chapter 8 from Elementary Differential Equations by Boyce. (Chapter 7 is nice to review as well)
• Chapter 6 from Classical Mechanics by Taylor (Calculus of variations)

Both books are used at UofT. I have not taken any physics courses nor numerical methods courses, so I found these resources particularly helpful in understanding the first lecture recording and for A1.