## non-trial solution...

how I can find an non-trial solution (non-zero) for differential equations?

Thanks

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## How to convert print to screen output to List form...

I wish to process a string of letters into a list of one or more characters which are comma separated at each change of character. The following function will achieve this, but its output is not as list [ ] in the format required.

Below is a routine to split a character string based on change of character: (ref: https://rosettacode.org/wiki/Split_a_character_string_based_on_change_of_character#Maple)

splitChange := proc (str::string) local start, i, len; start := 1; len := StringTools:-Length(str); for i from 2 to len do if str[i] <> str[start] then printf("%s, ", str[start .. i-1]); start := i end if end do; printf("%s", str[start .. len]) end proc;
splitChange("WPKCPYWYYYXHYY");#

Here is the output:
W, P, K, C, P, Y, W, YYY, X, H, YY

This print-to screen output is not usable, instead I need the output in list format i.e. ListY:= ["W", "P", "K", "C", "P", "Y", "W", "YYY", "X", "H", "YY"].

Background

In my model, each of these character strings is a node of a graph, and their adjacencies represent an edges of a graph.  I aim to automatically map strings into a set of directed adjacencies as output; for example:

AdjSet:= {[W, P], [P, K], [K, C], [C, P], [P, Y], [Y, W], [W,YYY],[YYY, X], [X, H], [H,YY]}.

This set will be the input to a directed graph, e.g:
from which our objective, the adjacency matrix of the nodes can be obtained in MAPLE.

Help

Can someone please help me by modifying the SplitChange rountine so that it produces output in the form of ListY above?

Thanks in anticipation of your help

Melvin Brown

## A question about output customization...

Hi,

In a recent post acer made me discover the joy of Typesetting to customize the outputs (acer, if you read this question: big thanks to you, really funny and powerful!)

I'm interested in using Typesetting for output coloring (for instance) but I would like that these outputs to be left justified.
Up to now I used to use printf to manage the outputs the way I wanted, but I failed combining Typesetting and printf.

Is it possible to exploit the capabilities of Typesetting in printf commands?
Or, at least, is it possible to "left-justify" print outputs programatically?

## Assume and Signum problem...

I have assumed lambda <-1 yet signum(lambda) returns lambda~.  It should be -1. I need to show that the expression lambda is used in is negative.

 Originally lambda, renamed lambda~:   Involved in the following expressions with properties     -real+lambda assumed `property/object`[0]     lambda+mu+nu assumed `property/object`[1]   also used in the following assumed objects   [-real+lambda] assumed 0   [lambda+mu+nu] assumed 1

 (1)

 Originally lambda, renamed lambda~:   Involved in the following expressions with properties     -real+lambda assumed `property/object`[0]     lambda+mu+nu assumed `property/object`[1]   is assumed to be: RealRange(-infinity,-1)   also used in the following assumed objects   [-real+lambda] assumed 0   [lambda+mu+nu] assumed 1

 (2)

 (3)

 (4)

## How to get back the plotting range when smartview=...

Hi,

When you do this a := plot(1/x, x=0..1);  the figure contains a "smart" graph which extends roughly from 0 to 30 in the vertical direction.
(no discont=true nor smartview=false used here, numpoints set to its default falue)

If you use plottools:-getdata(a); you find that the vertical range is about  0..1800.
It seems to mean that smartview=true (the default setting) overrides the range determined from the values of discont and numpoints?

My question is: Is it possible to retrieve the vertical range that plot uses when it displays the graph?

## Error, incorrect number of arguments to _Inert_FOR...

Hello Dr/Pof/Colleague

my target i want RUN double loop

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## Exporting two plots as one single EPS file...

I am developping an algorythm in which I need to obtain a 3D plot and its respective colorbars. As far as I know, Maple does not have a function with includes such a colorbar automatically (like Matlab, for example). So, I have had to get 3D plot and colorbar separatelly, as independent plots. It has worked fine, but now I need to export such graphics as EPS files, which imply merging them as a single graphic.

Here is a small example, where I try to put such graphics inside a table for then exporting it as EPS:

```restart:

with(plots):
with(DocumentTools):

graph:= plot3d(x^2+y^2, x = -10..10, y = -10..10, colorscheme = ["zgradient", ["Red","Blue"]]):

colorbar:= densityplot(axis_z, axis_x = 0..0.1, axis_z = grad_max..grad_min, style = patchnogrid, size = [100,250], axes = boxed, tickmarks = [0,10], labels = ["",""], colorscheme = ["zgradient", ["Red","Blue"]]):

tab:= Tabulate([graph, colorbar], exterior = none, interior = none, weights = [4,1]):```

It has not worked, though. Can anyone suggest a solution for that? I need to export both graphics as one single file, preferably EPS, because of its high resolution.

## Bug in inequal

Maple 2018

Let us consider

`plots:-inequal(max(1, min(x, 2))+max(1, min(y, 2)) <= 3, x = -4 .. 4, y = -4 .. 4);`

and compare it with

`plots:-implicitplot(max(1, min(x, 2))+max(1, min(y, 2)) = 3, x = -4 .. 4, y = -4 .. 4, gridrefine = 2);`

The latter plot must be a subset of the former plot, but it isn't so. bug_in_inequal.mw

## Problem with solve function after adding custom un...

Hi guys! First time posting here and I'm very new to Maple too.

I'm using maple right now to calculate statics problems, and for that we've customized some units to better fit what we're working with and want to see in output. In general, it's working great, but sometimes when I try to use the solve function including these units, I get an error mesage I don't really understand..

Here's the unit customization:

restart;
with(Units); AddSystem(NewSI, GetSystem(SI), kN*m, kN/m, kN, MPa); UseSystem('NewSI');

Error, (in Units:-AddSystem) expecting a unit but got `Units:-Unit(kN*m)`
with(Units[Natural]);

- As said, in general I have no problems, despite the error message above, it's only when using the solve function as follows:

(I've defined A,B,C and G, all with results in kN)
solve(OL-A-B-C-G=0,OL)

Then it gives me this error:
Error, (in Units:-Standard:-+) the units `1` and `kN` have incompatible dimensions

What I want here is to setup an equilibrium equation, and then solve for the variable OL, which should be output in kN.
First of all, I don't really understand what Maple is trying to tell me here?
-I figure it has something to do with the new units i'm adding, and when if I'm putting the units commands into the startupcode customizer, it tells me another error:
Error: (in Units:-AddSystem) expecting a unit but got `Units:-Unit(kN*m)

But I don't know how to do something about this, the new units I defne is simply something I've cpoy/pasted from another source, I don't have any knowledge about how to customize the system myself..
Googling this problem only leads me to the maple help websites, but that doesn't help me as I'm completely new to all this...

So I was hoping someone could help me fix the error(s), or at least understand what the errors mean..

## How can I put unequal error bars on an ErrorPlot i...

I have the following Maple code.

x := [5, 10, 15, 20];

y := [4.22, 7.49, 12.24, 19.60];

yui := [2.48, 3.76, 6.11, 14.60];

yli := [2.27, 3.34, 6.09, 10.90];

with(Statistics): with(plots):

p1 := ErrorPlot(y, coords = x, yerrors = yui);

this produces a plot with error bars. The problem is that I acutally have unequal errors. In the ErrorPlot helpfile it says:

"This options specifies errors along the x-axis. The array of errors must have the same number of elements. To specify right errors and left errors separately, use the list of two vectors." (this pertains to xerrors obviously but below it says the same applies to yerrors)

I have tried entering the code above with yerrors=[yli,yui] and with yerrors={yli,yui}....but neither option works and I get the error:

"Error, invalid input: Statistics:-ErrorPlot expects value for keyword parameter yerrors to be of type {identical(default), [{array, list, rtable, DataFrame, DataSeries}, {array, list, rtable, DataFrame, DataSeries}], {array, list, rtable, DataFrame, DataSeries}}, but received {[2.27, 3.34, 6.09, 10.90], [2.48, 3.76, 6.11, 14.60]}"

Can anyone advise me on what I'm doing wrong - I am very new to Maple.

Jo

## Why does obtain solutions for x give the wrong ans...

I have been trying to solve this equation by obtaining solutions for x and I actually handed in for an assignment what Maple gave me as an output. Then it turns out that Maple was wrong. This is in fact not a solution for the equation. What am I doing wrong here?
Solve_error.mw

## Why is maple unable to solve this equation? (4^x)+...

This is my first problem with Maple but i am pretty confused as to why it would struggle with these steps.

Just using a standard worksheet, here is what i have:

> f:=(4^x)+1

>g:=x^4

> solve(g=f,x)

now, i would just expect this to come back with 3 answers, but instead i get

Warning, solutions may have been lost
RootOf(-4^_Z - 1 + _Z^4)

if I do:

>fsolve(g=f,x)

It comes back with only one of the answers(2.094012853), instead of all three.

What am I doing wrong?

## How to solve this system with floors?...

I mean, for example,

```solve({4*x1+7*x2+6*x3 = 186, floor((1/2)*x1)+floor((1/5)*x2)+floor((1/3)*x3) = 18,
floor((1/5)*x1)+floor((1/2)*x2)+floor((1/4)*x3) = 21});
Warning, solutions may have been lost

```

A finite number of the solutions can be found by DirectSearch

```DirectSearch:-SolveEquations([floor((1/2)*x1)+floor((1/5)*x2)+floor((1/3)*x3) = 18,
floor((1/5)*x1)+floor((1/2)*x2)+floor((1/4)*x3) = 21, 4*x1+7*x2+6*x3 = 186],
{x1 >= -100, x2 >= -100, x3 >= -100, x1 <= 100, x2 <= 100, x3 <= 100},
AllSolutions, solutions = 3, number = 1000);

Matrix(3, 4, [[0., Vector[column](3, [0., 0., 0.]),
[x1 = 74.18778903830886, x2 = 58.93905207777524, x3 = -87.22075344961036], 185],
[0., Vector[column](3, [0., 0., 0.]),
[x1 = 71.22714241634635, x2 = 56.43467122661542, x3 = -82.32521137528222], 164],
[0., Vector[column](3, [0., 0., 0.]),
[x1 = 73.6407870507502, x2 = 58.33738250527096, x3 = -86.15413762331626], 165]])```

I don't see a way to obtain the MMA answer (in Maple notation)

```(155/2 < x1 and x1 < 78 and 744/7-4*x1*(1/7) < x2 and x2 < 62 or 72 <= x1 and x1 <= 73 and
102-4*x1*(1/7) < x2 and x2 < 62 or 73 < x1 and x1 <= 147/2 and 102-4*x1*(1/7) < x2 and
x2 <= 726/7-4*x1*(1/7) or 147/2 < x1 and x1 < 74 and 60 <= x2 and x2 <= 726/7-4*x1*(1/7) or
74 <= x1 and x1 < 75 and 726/7-4*x1*(1/7) < x2 and x2 < 62 or 153/2 < x1 and x1 < 78 and
726/7-4*x1*(1/7) < x2 and x2 < 60 or x1 = 72 and 58 <= x2 and x2 < 60 or 72 < x1 and x1 < 74 and
58 <= x2 and x2 <= 708/7-4*x1*(1/7) or 75 <= x1 and x1 < 76 and 102-4*x1*(1/7) < x2 and x2 < 60 or
x1 = 74 and 442/7 < x2 and x2 < 64 or 74 < x1 and x1 < 75 and 738/7-4*x1*(1/7) < x2 and
x2 <= 744/7-4*x1*(1/7) or 74 <= x1 and x1 < 75 and 708/7-4*x1*(1/7) < x2 and x2 <= 102-4*x1*(1/7) or
151/2 < x1 and x1 < 76 and 708/7-4*x1*(1/7) < x2 and x2 < 58 or 157/2 < x1 and x1 < 80 and
762/7-4*x1*(1/7) < x2 and x2 < 64 or 68 <= x1 and x1 < 137/2 and 56 <= x2 and x2 <= 666/7-4*x1*(1/7) or
x1 = 137/2 and x2 = 56 or x1 = 70 and 56 < x2 and x2 < 58 or 70 < x1 and x1 <= 71 and 56 <= x2 and
x2 < 58 or 71 < x1 and x1 < 72 and 56 <= x2 and x2 <= 690/7-4*x1*(1/7) or 70 <= x1 and x1 <= 281/4 and
54 <= x2 and x2 < 55 or 281/4 < x1 and x1 < 72 and 54 <= x2 and x2 <= 666/7-4*x1*(1/7)) and
x3 = 31-2*x1*(1/3)-7*x2*(1/6)```

## How do I fix my corrupted file?...

I get this message everytime I am trying to open my worksheet: "Recover Corrupt File and Save As"

2.G_anden_aflevering.mw

## How come i can't create variables or functions wit...

I've tried alot, but nothing seems to work. The problem occurres whenever im trying to use multiple SI Units in caculations that require division. Example: