# a math operator in UDF

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 May 24, 2005, 12:22 a math operator in UDF #1 lichun Dong Guest   Posts: n/a 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 Mark Guest   Posts: n/a 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 Mark Guest   Posts: n/a 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 lichun Dong Guest   Posts: n/a 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 Mark Guest   Posts: n/a 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 Saad Guest   Posts: n/a 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 Mahesh Guest   Posts: n/a 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) }

 June 18, 2005, 22:04 Re: a math operator in UDF #8 manish mehta Guest   Posts: n/a 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