Question: Vector Integration in Maple 2018 (compared to Maple 2017)

Is it possible to get the following integral involving vectors done in Maple 2018, but handle the singularity when p1=p3?

Note that the output of p3 and p1 are slightly different, probably because the earlier version of the worksheet was in Maple 2017? 

(Note: Earlier version - was due to help received from Dr. Edgardo Cheb-Terrab, using Maple 2017). 

 
with(Physics[Vectors]);
r_ := _i*x+_j*y+_k*z;
                    r_ := _i x + _j y + _k z
p__1_ := _i*`p__1x `+_j*`p__1y `+_k*`p__1z `;
           p__1_ := _i p__1x  + _j p__1y  + _k p__1z 
p__3_ := _i*`p__3x `+_j*`p__3y `+_k*`p__3z `;
           p__3_ := _i p__3x  + _j p__3y  + _k p__3z 
Expression to integrate wrt p3
'exp(i*(p__1_ . r_))/((p__3_ - p__1_)^2)'
             exp(I Physics:-Vectors:-.(p__1_, r_))
             -------------------------------------
                                                2 
              Physics:-Vectors:-+(p__3_, -p__1_)  
Delaying the evaluation above, if evaluation is allowed, the integrand is
exp(I*(p__1_ . r_))/(p__3_-p__1_)^2;
(exp(I (p__1x  x + p__1y  y + p__1z  z)))/((_i (-p__1x  + p__3x )

   + _j (-p__1y  + p__3y ) + _k (-p__1z  + p__3z ))^2)
T i is the imaginary unit
interface(imaginaryunit = I);
                               I
Because (4), has the value of i before being the imaginary unit, input the integrand again
'exp(i*(p__1_ . r_))/((p__3_ - p__1_)^2)'
             exp(I Physics:-Vectors:-.(p__1_, r_))
             -------------------------------------
                                                2 
              Physics:-Vectors:-+(p__3_, -p__1_)  


Now on the integration
Int(exp(I*(p__1_ . r_))/(p__3_-p__1_)^2, [`p__3x ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity]);
  /infinity   /infinity   /infinity                            
 |           |           |                                     
 |           |           |          (exp(I (p__1x  x + p__1y  y
 |           |           |                                     
/-infinity  /-infinity  / -infinity                            

   + p__1z  z)))/((_i (-p__1x  + p__3x ) + _j (-p__1y  + p__3y )

   + _k (-p__1z  + p__3z ))^2) dp__3x  dp__3y  dp__3y 
value(Int(exp(I*(`p__1x `*x+`p__1y `*y+`p__1z `*z))/(_i*(-`p__1x `+`p__3x `)+_j*(-`p__1y `+`p__3y `)+_k*(-`p__1z `+`p__3z `))^2, [`p__3x ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity, `p__3y ` = -infinity .. infinity]));
                                         /         /[          
 exp(I (p__1x  x + p__1y  y + p__1z  z)) |PIECEWISE|[infinity, 
                                         \         \[          

   Im(_i p__1x  + _j p__1y  + _k p__1z  - _k p__3z )    ]  
   ------------------------------------------------- = 0], 
                          _i                            ]  

                 \\         
   [0, otherwise]|| infinity
                 //         
In the above, there is the product of three Dirac delta functions, that can be represented as a single 3D Dirac delta
combine(exp(I*(`p__1x `*x+`p__1y `*y+`p__1z `*z))*piecewise(Im(_i*`p__1x `+_j*`p__1y `+_k*`p__1z `-_k*`p__3z `)/_i = 0, infinity, 0)*infinity);
                                         /         /[          
 exp(I (p__1x  x + p__1y  y + p__1z  z)) |PIECEWISE|[infinity, 
                                         \         \[          

   Im(_i p__1x  + _j p__1y  + _k p__1z  - _k p__3z )    ]  
   ------------------------------------------------- = 0], 
                          _i                            ]  

                 \\         
   [0, otherwise]|| infinity
                 //         

 

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