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a math operator in UDF

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Old   May 24, 2005, 12:22
Default a math operator in UDF
  #1
lichun Dong
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hi, All:

How to get the reminder of two number in UDF, like 7.2 % 2 = 1.2 in C. I need to input a asymmetric moving wall condition which has a period of 2*pi. I tried % in UDF, it does not work. Anybody has an experience?

Thanks a lot
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Old   May 24, 2005, 13:12
Default Re: a math operator in UDF
  #2
Mark
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I believe you use the div command to store the quotient and remainder. Then access the remainder using .rem

Example:

divide = div(numerator,denominator); remainder = divide.rem;

Mark
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Old   May 24, 2005, 13:13
Default Re: a math operator in UDF
  #3
Mark
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Sorry, the example came out poorly formatted.

Example:

divide = div(numerator,denominator);

remainder = divide.rem;

Mark
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Old   May 24, 2005, 15:34
Default Re: a math operator in UDF
  #4
lichun Dong
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hi, Mark:

Thanks a lot, so what is the data type of divide? Array of real?

Lichun
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Old   May 24, 2005, 15:56
Default Re: a math operator in UDF
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Mark
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Hi,

Sorry, I should have included that with the example. I declared the variable using:

div_t divide;

So that would make it a type "div_t" (I think).

Mark
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Old   May 29, 2005, 07:53
Default Re: a math operator in UDF
  #6
Saad
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I think you can use the function rem(a,b). For example, rem(5,3) = 2.

Saad
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Old   June 7, 2005, 10:11
Default Re: a math operator in UDF
  #7
Mahesh
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I have used once to define square wave velocity function as below. ================================= #include "udf.h" DEFINE_PROFILE(sq50_velocity, thread, nv) { face_t f; real t= RP_Get_Real("flow-time"); int p,q; real T=0.01; p=t/(T/2); q=p%2;

begin_f_loop(f, thread) { if(q==0)

F_PROFILE(f, thread, nv) =30;

else

F_PROFILE(f, thread, nv) = 0; } end_f_loop(f, thread) }
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Old   June 18, 2005, 22:04
Default Re: a math operator in UDF
  #8
manish mehta
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Dear Mahesh,

I am really new with UDF files. If my square wave needs to go from 180 psi to 0 psi, and it has a frequency of 10 Hz. How would I go about doing this?

I thought of doing a Fourier Transform of a square wave that I need, but there are problems with that approach. Any advice would be benefical.

Hope you can help. -Manish
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