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WWenx's avatar
WWenx
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7 years ago

ALTFP_MATRIX_INV IP core output wrong result

I use the IP core ALTFP_MATRIX_INV of 4*4 matrix inversion, but the result of inversion output is wrong. The output of a full rank matrix (e.g. {1,2,0,0;3,4,0,0;0,0,0,0,1,0;0,0,0,0,1}) is an abnormal...
CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
7 years ago

Hi,

Sorry for the delay. As I understand it, you observe some issue with the ​ALTFP_MATRIX_INV IP in Modelsim simulation. To ensure we are on the same page, would you mind to further elaborate on the following:

  1. What is the device that you are using and Quartus version?
  2. Thanks for attaching screenshot. To facilitate further understanding, would you mind to further elaborate on the output result that you are expecting and also probably add some markers on the screenshot on the section that you observe issue. For example, with specific input, the expected result vs wrong result in the simulation.

Thank you very much for your help.

Best regards,

Chee Pin

  • WWenx's avatar
    WWenx
    Icon for New Contributor rankNew Contributor
    7 years ago

    Hi,

    ​

    Thanks for you reply. I tested two sets of data.

    The first set of data, the matrix that I put in is {1,0,0,0; 3,4,0,0; 0,0,1,0; 0,0,0,1}, ture inverse of this matrix is {1,0,0,0; -0.75,0.25,0,0; 0,0,1,0; 0,0,0,1}. BUT I got the wrong result is an abnormal number (NAN) in Modelsim simulation and in Signaltap Ⅱ. As picture 1,2,3,4 show.

    Second set of data, the matrix that I put in is {35,-20,0,0; 20,35,0,0; 0,0,1,0; 0,0,0,1}, ture inverse of this matrix is {0.021538,0.012308,0,0; -0.012308,0.021538,0,0; 0,0,1,0; 0,0,0,1}. BUT I got the wrong result is {0.0424242,-0.0242424,0,0; -0.0242424,0.0424242,0,0; 0,0,1,0; 0,0,0,1} in Modelsim simulation and in Signaltap Ⅱ. As picture 5,6,7,8 show.

    1. I use EP4SGX530C2 FPGA ,and Quartus 15.0
    2. The following pictures are in order 1,2,3...

    Thank you very much for your help.

    Best regards,

    Wenxiang

  • WWenx's avatar
    WWenx
    Icon for New Contributor rankNew Contributor
    7 years ago