## 29 Reputation

14 years, 289 days

## How to take derivative of sum?...

Maple

I have the following expression.

What I want to do is take the derivative of this expression with respect to,

Where L is somewhere between 1 and n.

Using the diff operator, I would like to get something like,

But I don't.  Instead, I get zero.  I want to leave n undefined so that the summation isn't automatically expanded out to alot of terms, thereby making it much more difficult to read.  This is especially true as my formulas become more complicated.

Thanks!!

## Warning - Solutions may have been lost...

Maple 13

Hi, I am trying to isolate the following expression for omega

a*(cos(omega)*cos(beta*omega)+b*sin(omega)*sin(beta*omega))+c*sin(beta*omega) = 0

However, when I try to do so I get a Warning - solutions may have been lost

Thanks for any help that can be offered

## Creating a colorbar for a contour plot...

Maple

Hi, I have not found a post that explains how to create a colorbar for a contour plot with or without filled regions.  At the moment, I manage to create a color bar manually as follows.

First, I plot some function like so,

plots[contourplot](i/(1-(1+i)^(-n)), n = 15 .. 30, i = 0.1e-1 .. .15, axes = frame, contours = [seq(0.1e-1*n, n = 5 .. 16)], filledregions = true, axis[1] = [location = low, gridlines = [10, majorlines = 1]], axis[2] = [location = low, gridlines = [10, majorlines = 1...

## Phase diagrams with a system of more the...

Maple

Hi, I have a system of four first order, nonlinear, differential equations with four dependent variables.  The variable F(t) can be set equal to zero or to some known function.

A*(diff(xx(t), t)) + epsilon*xx(t) + B*(diff(phi(t), t))*cos(theta(t)) + C*phi(t)^2*sin(theta(t)) = F(t),

D*(diff(xx(t), t))*cos(theta(t)) + E*diff(phi(t), t)) + F*sin(theta(t)) = 0,

xx(t) = diff(x(t), t),

phi(t) = diff(theta(t), t)

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