Hi all, I am switching from Maple slowly to Mathematica. Here is a PDE problem, which is sovable in Maple, but I can't seem to get it work in Mathematica. This is just a "small" example I took. In my work sheet, I have attached the problematic PDE. I am not sure whether it's the double subscripts that I have used, so I tried to change to a set of simpler variables. For those who are instersted, I have also attached the "solution" from using Maple (PDF format). FF = f[a, b, c, d] eq1 = D[FF, d] + (1 - a)D[FF, a]/d == 0 eq2 = D[FF, c] + (b - (a - 1)d)D[FF, a]/(cd) == 0 eq3 = D[FF, b] + D[FF, a]/d == 0 DSolve[{eq1, eq2, eq3}, {FF}, {a, b, c, d}] And I expect Mathematica to give something like a valid solution, such as (from Maple) FF = (-b + (a - 1) d) c Many thanks! Attachments:

Hi Udo, I dont know much how PDE (or DE). But say if I just want to get something like the output from Maple (see the Maple PDF), is that possible? So f is a function: f = (-b+(a-1)d)c and it is a valid solution to this system. Many thanks!

Frankly spoken, I do not see it. The net knows, that one has to tinker a bit in the case of a partial differential equations system under Mma, compare e.g. http://mathematica.stackexchange.com/questions/42326/how-to-solve-a-system-of-partial-differential-equations there is also an informative manual from Wolfram Research [url=http://www.google.ch/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDcQFjAB&url=http%3A%2F%2Fwww.wolfram.com%2Flearningcenter%2Ftutorialcollection%2FDifferentialEquationSolvingWithDSolve%2FDifferentialEquationSolvingWithDSolve.pdf&ei=aOJlU-jSN6mh0QWZy4C4BA&usg=AFQjCNEjW4Lug2dR5_fShPwL7gBFVStCNA&bvm=bv.65788261,d.bGQ]http://www.google.ch/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDcQFjAB&url=http%3A%2F%2Fwww.wolfram.com%2Flearningcenter%2Ftutorialcollection%2FDifferentialEquationSolvingWithDSolve%2FDifferentialEquationSolvingWithDSolve.pdf&ei=aOJlU-jSN6mh0QWZy4C4BA&usg=AFQjCNEjW4Lug2dR5_fShPwL7gBFVStCNA&bvm=bv.65788261,d.bGQ if not successful on the direct way, one does usually the following: make an educated guess (* a so called ansatz *) and solve the ansatz. Actually one would do a power series in four variables, producing recurrence relations for the coefficient a[n1,n2,n3,n4] and trying to solve them using RSolve[].

Hi Udo, Yes, I knew that manual you were referring to. However, it is only a "small" system i used to adress the problem here. I have many and much larger PDE systems, which were formed from my research problems. So I dont think my focus is on the PDE here. If I have the time, I will stick with Maple for this matter. Because Maple works. I tried the example on stackexchange. In my case, it does not work. Again, it's just not what i was expecting. I want something simple so I can apply it to many other (similar) PDEs. Many thanks for your help though!!

DSolve does not solve this