odd jit.expr behavior


    Jun 19 2006 | 11:15 am
    Maybe I'm doing something with jit.expr that I'm not supposed to, but can someone explain the result of this little patch?
    It prints out "0 0 0 0" in the max window when you press the bang button. I would expect that using a constant in jit.expr would output that constant, not 0. I'm not saying that this is a bug, but it's what I would expect jit.expr to do in this case.
    In the end, what I'd like to do is replace everything in a few specific planes of an incoming matrix with a constants. I just wanted a simple patch that created a "noisy" hue along very specific lines, and held the saturation and luminosity of the video constant, but due to the problem (or my misunderstanding) above, it doesn't work that way I'd like:
    Best, Evan

    • Jun 19 2006 | 11:44 am
      sorry, I should have read the fine print first before sending this example - jit.expr only supports float32. Duh.
      But there's still the same unexpected behavior using float32 - in this new patch, try first banging jit.expr - it will print "0. 0. 0. 0." to the max window. Then, try banging the jit.matrix - it will print the correct constants "1. 0.5 0. 0.1" to the max window. Since jit.expr is only supposed to print out the constants defined in it's expression, i'd consider this at least bug-like - it shouldn't matter whether or not i send it a valid matrix, those constants should always come out, or an error, but especially not "0 0 0 0".
      Best, Evan
    • Jun 19 2006 | 2:13 pm
      I beleive that jit.expr only supports float32 matrices. wes
    • Jun 19 2006 | 3:43 pm
      Thanks for pointing this out, Evan. I can reproduce here.
      FWIW, jit.expr converts all types to float32 internally, so it will be less efficient with other data types, but it should still work (assuming the data easily converts to float32). This appears to be a different thing altogether.
      Until we can fix this behaviour, the simple workaround is to either use the "setall" jit.matrix message or always send a matrix through jit.expr.
      Cheers, Andrew B,
    • Jun 19 2006 | 5:26 pm
      Great. The workaround is fairly easy, I did wind up using setall. Luckily, I'm dealing with very small matrices and so sending them to jit.expr each time isn't a problem this time, either. Thanks for taking a look at it.
      Best, Evan