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May 24, 2005, 12:22 
a math operator in UDF

#1 
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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 

May 24, 2005, 13:12 
Re: a math operator in UDF

#2 
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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 

May 24, 2005, 13:13 
Re: a math operator in UDF

#3 
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Sorry, the example came out poorly formatted.
Example: divide = div(numerator,denominator); remainder = divide.rem; Mark 

May 24, 2005, 15:34 
Re: a math operator in UDF

#4 
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hi, Mark:
Thanks a lot, so what is the data type of divide? Array of real? Lichun 

May 24, 2005, 15:56 
Re: a math operator in UDF

#5 
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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 

May 29, 2005, 07:53 
Re: a math operator in UDF

#6 
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I think you can use the function rem(a,b). For example, rem(5,3) = 2.
Saad 

June 7, 2005, 10:11 
Re: a math operator in UDF

#7 
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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("flowtime"); 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) } 

June 18, 2005, 22:04 
Re: a math operator in UDF

#8 
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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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