I want to apply heat on a tube surface (3D). The heat is to be applied on a straight line on the tube. The equation of line is

x= 87.5

y = 126.1620 + (-1*1004.0820)

z= 166.1620 + (-1*-1004.0880)

Since x is constant is given asposition holder, real x[ND_ND];

For this constant value of x, heat is appiled on the line with the equation above. (If y and z are satisfied.

I have created my code below and when I try to interprete it, there is an error report:

Error line 16: invalid type for &&: float && float.

This is the line 16

((y = 126.1620 + (-1*1004.0820)) && (z= 166.1620 + (-1*

-1004.0880)));

How do I correct the error?

```
#include "udf.h"
/* profile for heat flux*/
DEFINE_PROFILE(heatflux_profile, t, i)
{
/* declaring variables */
real x[ND_ND]; /* this will hold the position vector */
real y;
real z;
face_t f;
begin_f_loop(f, t)
{
F_CENTROID(x, f,t);
if
((y = 126.1620 + (-1*1004.0820)) && (z= 166.1620 + (-1*
-1004.0880)));
F_PROFILE(f, t, i) =500;
else
F_PROFILE(f,t,i)=350;
}
end_f_loop(f, t)
}
```