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About yahastu

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  1. Got it working.  The trick was modifying the list of semicolon delimitted items manually rather than via clicking on it and using the built-in path list editor.
  2. I tried adding the paths to "Configuration Properties => C/C++ => General => Additional Include directories" and "Configuration Properties => Linker => General => Additional Library directories" (in addition to the Microsoft.Cpp.Win32.user properties), and also changed the include files to specify the full-path location to the D3DX headers as in your example, but there is no change. Perhaps the problem lies with the fact that I cannot use an absolute path to specify the library name -- eg, in "#pragma comment (lib, "d3d11.lib")" and so, it may continue to look for the library in the Windows 7 sdk first.... It seems like this would be a problem for all Windows 7 users that attempt to use DirectX...there must be a common resolution
  3. Why use D3DX? I understand that D3DX is deprecated and replaced by DirectXMath in the Windows 8 SDK.  However DirectXMath is not included in the Windows 7 SDK, and neither is D3DX...which means that there seems to be no "proper way" to access these basic utility functions.  I have heard that it may work to use the Windows 8 SDK for development on Windows 7, however, that doesn't sound entirely reliable to me...and I'm not interested in developing Windows 8 apps at this time anyway.  I would like to utilize some of my older code that is written using D3DX for this project and so I prefer to stick with that for now.  Therefore, I am trying to use the last DirectX SDK frome June 2010. What's the problem? After installing the DirectX SDK, and added the new include and lib paths under the Win32.User properties page in Visual Studio (as explained in the answer here ), and add the following includes:   #include <d3d11.h> #include <d3dx11.h> #include <d3dx10.h>   #pragma comment (lib, "d3d11.lib") #pragma comment (lib, "d3dx11.lib") #pragma comment (lib, "d3dx10.lib")   ...and now, although I can use certain D3DX functions like D3DXCOLOR,  I get unresolved external symbol errors for certain functions like D3DXCompileFromFile and D3D11CreateDeviceAndSwapChain.  I think the problem is that d3dx11.h exists in two places:   C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Include C:\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Include   In other words, the D3DX headers conflicts with the headers already present in the built in windows SDK, and I cannot even remove those built in include paths or give my include path priority over them (at least I don't know how). How can I resolve this issue?
  4. Kalman filter predict/update equations are here: https://en.wikipedia.org/wiki/Kalman_filter   I have implemented the Kalman filter and it works nicely.  However,  the standard Kalman equations are written naively in terms of the matrix inverse.  In particular, the S matrix (innovation covariance) is inverted in order to compute K (the gain matrix): S = H P H^t + R K = P H^t S^{-1} The gain matrix (K) is finally used to update the state estimate (x) and estimated covariance of the state (P) as follows: x += K y P -= K H P I would like to update 'x' and 'P' without computing the matrix inverse S^{-1}. In the following reference, a method is given "for calculating (H P H^t + R)^{-1} H in the conventional Kalman filter without explicitly computing an inverse." (using U D U^T, or LDL^t)  Of course, (H P H^t + R)^{-1} is equal to S^{-1}, but this confuses me because "S^{-1} H" does not appear in the computation of K....and so, it is not clear to me, how the value of S^{-1}H can be used to compute K. Reference: 'Kalman Filtering; Theory and Practice Using MATLAB', second edition, by Grewal and Andrews http://books.google.com/books?id=sZbxLK-NKb0C&q=+without+explicitly+inverting#v=snippet&q=without%20explicitly%20inverting&f=false (click the second link)
  5. Thanks for your reply Alvaro.  If I can rearrange the nasty equation into a polynomial in t, then yes I can easily find the roots of it.  The difficulty is in automatically calculating the coefficients of this polynomial, given that it is a summation of terms such as "a_N*(a_x+b_x*t)^N" which would effect the coefficients for ALL terms less than N. I think that implicitizing the equation might just come down to constructing an appropriate matrix and taking the determinant, after which point I'd have two parametric equations with two unknown parameters, should should be solvable...so I'm not sure which approach is actually easier
  6. I have a polynomial curve defined by a set of coefficients (a_0, a_1, a_2, ... a_N ):   y(x) = a_0 + a_1*x + a_2*x^2 + ... a_N*x^N I also have a parametric line:   p(t) = a + b*t I wish to find the value of "t" such that the parametric line intersects with the polynomial curve. Clearly, the first step is to expand the parametric equation: p_x(t) = a_x + b_x*t p_y(t) = a_y + b_y*t Plugging in, I get this nasty thing: a_y + b_y*t = a_0 + a_1*(a_x + b_x*t) + a_2*(a_x+b_x*t)^2 + a_3*(a_x+b_x*t)^3 + ... I have no idea how to solve this for "t". I want a numerical solution that works for arbitrary N, so I'm not expecting to find a closed form solution...I'm fine using any linear algebra or minimization techniques to get the answer, I'm just not sure what the most effective method would be. Edit: I'm thinking that perhaps the proper approach is via "curve implicization" to convert the polynomial curve into a parametric form, thereby making it easier to compute the intersection.  I found this paper and I think it may be possible to implicitize this polynomial curve by using Sylvester's matrix elimination method as briefly described here ( http://www.cs.cmu.edu/~hulya/Publications/IJCV03Paper.pdf , p107 )...but I'm still a bit confounded.
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