The pH levels of a lake controls the conc. of harmless ammonium ions(NH₄⁺) and toxic ammonia (NH₃) in the lake.

For pH levels <8, conc. of ammonium ions are little affected by pH changes, but decline over many orders of magnitude as pH levels increase beyond pH 8.

Toxic ammonia are negligible at low pH , increase over many orders of magnitude as the pH level increases and reach a high plateau at about pH =10 (after which, NH₃ are little affected by pH changes).

How do I illustrate this graphically?

Percentage survivorship is a function of time; there ia negligible decline in survivorship at pH=6, marked decline in survivorship at pH=3.5, resulting in no survivors after just 8 hours.

What is the function for this problem and how do I plot it in Maple?

Hi all,

I have the following expression,

where K and K_P are the controller gains, k is the stiffness, b is the damper, m1 and m2 are masses.

How can I find the condition on variables such that the numerator of this expression is greater that zero?

The conditions should appear as inequalities.

Download Routh-Hurwitz_stability.mw

with(PDEtools):
V:=-exp(I*(k*x+omega*t+theta))*sqrt((k^2+omega)/(k*sigma))*sech(sqrt(k^2+omega)*(-2*k*t+x));
pde[1] := simplify(I*(diff(V, t, t))+diff(V, x, x)-I*sigma*V*(conjugate(V)*(diff(V, x))-V*(diff(conjugate(V), x)))) = 0;

What wouldn't work in Maple 2018 if I removed the Microsoft Visual C++ 2015 redistributable?  I have older versions of the C++ redistributable packages (ie 2013).  I hadn't noticed anything unusual when I initially removed it but maybe there's something that's affected in Maple?  Code generation package routines maybe?  What commands in Maple would be affected?

Reason is, I'm getting errors with another software and re-installing the 2015 C++ redistributable isn't installing properly.  So I'm just hoping there's no issues using Maple without the C++ 2015 redistributable being installed properly. 

Is it possible to split an execution group containing 2D input?
(without conversion to 1D which destroys the format).
Using F3 or the menu seems to work only for lines with a prompt.
But usually an execution group has a single prompt; lines with prompts appear e.g. when two execution groups are joined (with F4).
Is copy&paste the only solution?

I was recently cleaning up a worksheet to make things more succinct.  In that process I modified how I expressed the series coefficients, Ck.  What seemed to be an innocous change apparently upset MAPLE to the point it cannot process my results.  In the abbreviated worksheet link below I process the results in the previous manner, Ck1, as opposed to my current modification, Ck2.

In the previous manner the results are generated under 3 minutes.  After modifying the expression for Ck, MAPLE cannot seem to process the results at all.  As far as I can tell the Ck1 & Ck2 concur.  So I am perplexed.  Can anyone see what is wrong?  The only thing I can think of is that sin(2*pi*k/T*x) in the denominator might cause the problem.  However, the sin term is cancelled out by the same sin term in S4.

Ck_modification.mw

Hi Mapleprimes,

I have tried to search solutions online without luck. My problem is this. Suppose I have three equations:

f(x,y,z)

g(x,y,z)

h(x,y,z)

I would solve using solve({f,g,h},{x,y,z}) which would give me solutions x*, y* and z*. I need to assign the solutions to use them in subsequent computations. I would like to impose non-negativity constraints, however. Hence, the solution of x is max(x*,0). Obviously if a non-negativity constraint binds, this affects the solutions of y* and z*. I would like to assign the solutions taking this into account. How would you propose I do this? Bear in mind that the solution of x* might be a-b where the relative magnitudes of paramenters a and b are not given. Further down in my code, I would like to assign values to parameters and then let Maple give me the solutions with the non-negativity constraints. I hope I am making sense.

Thanks very much in advance.

Best,

Christian

I want to use Burr distribution and hence I am creating custom probability distribution. The pdf of Burr is not piecewise. It gives error.

burrpdf := alpha*k*((x-gamma)/beta)^(alpha-1)/beta(1+((x-gamma)/beta)^alpha)^(k+1)

burr_distribution := Statistics[Distribution](PDF = (alpha > 0, beta > 0, gamma > 0, k > 0), burrpdf)

Error, (in Statistics:-Distribution) invalid input: too many and/or wrong type of arguments passed to NewDistribution;

I've been using Maple 2018 only a few days now, was mostly using Maple 2016 and never had any issues with returning an output (at least one that wasnt my fault), but with 2018 I've seen a few times where a simple task would return an output of "__SELECTION" and then my input. No idea what this is or why its happening and all I really need to know is how to prevent it from happening. If its something with my preferences or settings that needs to be addressed, thats fine, but otherwise this is getting to be a real pain. See attached 

I have a function involving sinh(x)/cosh(x) to evaluate (see attached SKS77.mw and S77.pdf). I got different values depending on whether or not the function is algebraically simplified. What's the right way to evaluate the exponential function in this case? Thanks

Hello

I was trying to introduce vector r_vec that has 3 components in x,y,z

I've attached my file, I've 2 questions here

first, why isn't the vector shown in as r_vec = () ei + () ej + () ek instead appears as a column vector

second, why doesn't it accept differentating

thank you
 

Download tst1.mwtst1.mw

I have the following pertubation problem I want to use maple to expand for me.

We have epsilon := eps;

x(t,eps):= x_{-1}(t)/eps+x_0(t)+x_1(t)*eps

z(t,eps):=z_{-1}(t)/eps+z_0(t)+z_1(t)*eps

I want to expand a Taylor series of the following function upto some arbitray order of eps, i.e O(eps^3) or higher (depending on my mood :-)), around t=0, f(x(t,eps),z(t,eps),cos(t/eps),sin(t/eps)).

Anyone has any suggestion how to use maple 2017.3 to do this?

Thanks!

Hello Guys, I hope you are all fine. I have been struggling with creating an animation of the points (x,y) in maple. I have tried this example 
L := [[1, 1], [3, 2], [3.4, 6], [5, 3, 7], [3, 7, 9, 1], [2, 6, 8, 4, 5]];
animate(PointPlot, [L[trunc(t)]], t = 1 .. 6, frames = 150)
but in my case it shows two points at different location means it takes x and y seperate value and showed it on 1 and 2 on x axis but i want to animate it as the location of point. Please help me. 
Thank you in anticipation.

I have several functional equations in equally many unknown functions of at least two variables, plus parameters.  ("collect" works just for single equations, right?)

I know that for certain parameter ranges, all the functions involved will be quadratic, and I know some coefficients are zero.  That gives me some  coefficients to determine.  I want to

1. specify the functional equations [done in a very primitive low-tech way in the attachment, using atomic variables rather than indices ... have I done correctly?!?] 
2. get Maple to collect coefficients (the K's and the L's in the attachment; the variables are (y,z))
3. get Maple to state an equation system these coefficients have to satisfy (these will unfortunately be coupled quadratics)
4. get Maple to solve that equation system if possible, and if not: to tell me when (= for what parameter values, parameters being the "remaining letters" in the attachment) I have specified enough coefficients
5. in case of a solution, get Maple to tell me which coefficients are real and positive (for those that are solution of quadratic eq's: whether a positive solution exists)

Phew. I am still a complete newbie. Edit: Attachment link: STcoeff2match.mw where the equations themselves are EQ0, EQ1 and EQ2 at the bottom. Copying and pasting them, they look like this (download STcoeff2pastedEQs.mw)