Hello,
I'm working on coupled differential equation.
The first system is : 
y₁''+y₁'+y₁=q₁
q₁''+e(q₁²-1)q₁'+q₁=y₁"

And the second one : 
y₂''+y₂'+y₂=q₂
q₂''(t)+e(q₂²-1)q₂'(t)+q₂(t) = y₂"+f(P) q₁(t-tau)

This is a parametric system, f(P) and tau(P) are given function of the parameters P.
e is a constant

I have solved the first system with dsolve (using numeric option).
But when I try to solve the second one (with dsolve, numeric, setting P as a parameter), maple returns an error : 

"Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {t, t-1}"

I think Maple doesn't like " q1(t-tau)".
I have tried to create a new function q where :
q(t)=q1(t-tau)
But Maple returns the same error.

How can I fix it ?

Thanks for reading

EDIT : I have read there is no function in maple that solve delay differential equation.
But this is not a true DDE because q₂ has no effect on q₁. 
So I hope there is a way to "fool" maple and still use dsolve.

EDIT 2 :
I have found how to make it works.
I was using dsolve with the option compile (which increase (a lot) the efficiency of computation).
I delete this option and that's working.
Nevertheless, without the option compile, the computation is very very slow.
MapleHelp recommands to combine the 2 systems for more efficiency. But, when I combine, maple return the previous error.
How can I make it quicker ?

Here is the code : 

test_2_cylindre_sans_compile.mw 

Hello, I was trying to control color of a plot3d. 
I find this answer : http://www.mapleprimes.com/questions/148397-Plot3d-Color-Range
And this post of @Carl Love : 
"

Here's how to do it with a continuous transformation to your existing color function, which is presumed to return a value between 0 and 1 (the HUE color scale). Keeping it continuous is very very nice when you want colors to represent  numeric values. Let's say your existing color function is C, and your coordinate functions for a parametrized surface are Fx, Fy, Fz.

Gamma:= 1.15:
plot3d(
     [Fx, Fy, Fz],  a..b, c..d, 
     color=  [
          (x,y)-> (1-C(x,y))^Gamma/3, #Hue
          (x,y)-> 1-C(x,y)/4,         #Saturation
          (x,y)-> 1-C(x,y)/7,         #Value
          colortype= HSV
     ],
     lightmodel= NONE,
     style= patchnogrid     
);

There are several parameters that can be adjusted; I've chosen some of them by my personal taste for color .

• Gamma controls the evenness of the distribution between red and green. I gave this one a name because this is a well-known concept (see the Wikipedia article "Gamma correction").
• The 3 in the Hue selects the fraction (1/3 in this case) of the full color spectrum that you want. If you want green to red, it will need to be pretty close to 3.
• The Hue value is subtracted from 1 to make the scale go green to red rather than red to green.
• The 4 in the Saturation controls (to some extent) how "light" the light-green is.
• The 7 in the Value controls (to some extent) how dark the dark-red is (lower values will make it darker).
• lightmodel= NONE is used so that the colors will not change due to shadows when the plot is rotated. "

I made some test to see the impact of the Gamma parameter. 
And with Gamma = 1, it's odd. 

It looks like with gamma = 1, plot3d makes an automatic scaling of the colors.
But I don't understand why.
Does anyone know ?

Download oddity.mw

Hello, 
I have tried to make a densityplot with a logarithmic scale on one axis using : 

So the plot is displayed with a log scale but the grid used to generate the plot is still linear, with a regular spacing.
I don't know how to make it logarithmic too. 
Maybe it's not very clear. For example I would like  a spacing of 0.1 from 0.1 to 1 then a spacing of 1 from 1 to 10.
How can I do that ? 
I have not find any clue in the help ...

EDIT : The option "axis[1]=[mode=log]" only change how the plot is displayed.
I would like to change the grid, that is to say how the plot is calculated.