## trouble with basic linear equations...

I'm having some trouble maybe someone can point out my error please. I'm using the Maple 18 worksheet to try some basic linear equations. The trouble is in the last step.

Then I put in my formula to discover the slope. I confirm it looks correct in the Variables window.

m := (y2-y1)/(x2-x1);

2.)  Next I input the values for my ordered pairs. I also confirm thru the Variables window.

x1 := 2;

y1 := 14;

x2 := 3;

y2 := 18;

3.) Now I can type m and expect to get an answer to what my slope is.

m;

4.) Now I want Slope/Intercept form of y=mx+b. When I put in the formula y-y1=m(x-x1) i get a strange result

When I execute this formula, the result is y-14=4. (or thru context menu I tell it to solve for y, then I get y=18)

y-y1=m(x-x1)

When I manually input the values, the output is y-14=4x-8 (or thru context menu I tell it to solve for y, then I get y=4x+6)

y-14 = 4*(x-2)

Why is my equation (y-y1=m(x-x1)) not executing properly?

## PlotExpression in mini course not working?...

This is one is for Edgardo: In the "mini course", there is a command "PlotExpression" used that does not seem to do anything, at least for me. This is in a fresh Maple 18.01 installation on Linux with the latest version of Physics pulled off the Web today.

I cannot find any reference to PlotExpression in the Maple Help files, so where is this thing supposed to be defined? I >am< running a .mapleinit file of my own, configuring some of the plots[setoptions] parameters to my liking, but it should not clobber anything from the system mapleinit.

Another person managed to get the definition of PlotExpression and send it to me. From that I can see that the underlying plots:-plotcompare command seems to work, at least in part.

???

USPAS

## fsolve cannot solve this equations and return them...

hello

this is my program and fsolve for low intensity solve the equations but for high intensity cannot solve why?

this is my code:

ep0 := 1/(4*3.14);

el := 8.54*10^(-2);

hbar := 1;

vf := 1/300;

kb := 1;

tem := 2.586*10^(-2);

ci := 1;

p := 1.458*10^16;

beta := 2;

ai := 7.1*10^(-4);

bi := ai/sqrt(3);

enph := .196;

d := enph/(kb*tem);

n0 := 1/(exp(enph/(kb*tem))-1);

gama := hbar*vf;

intensity:=9000000

w := 7.28;

impurity := 7.2*10^3;

g := hbar*beta/(bi^2*sqrt(2*p*enph));

aa := g^2*(n0+1)/(2*Pi*hbar*gama^2);

bb := g^2*n0/(2*Pi*hbar*gama^2);

cc := 2/(Pi*gama^2);

l := (1*hbar)*w/(2*kb*tem);

u := el^2*intensity/(32*w*hbar^2);

[fsolve({op([((enph*ln(1+exp(c+enph/(kb*tem)))/(kb*tem)-polylog(2, -exp(c))+polylog(2, -exp(c+enph/(kb*tem))))*enph*(kb*tem)^2-(enph^2*ln(1+exp(c+enph/(kb*tem)))/(kb^2*tem^2)+2*enph*polylog(2, -exp(c+enph/(kb*tem)))/(kb*tem)+2*polylog(3, -exp(c))-2*polylog(3, -exp(c+enph/(kb*tem))))*(kb*tem)^3+(-exp(b)*enph*ln(1+exp(c+enph/(kb*tem)))+exp(c+d)*enph*ln(1+exp(b-d+enph/(kb*tem)))+exp(b)*kb*tem*polylog(2, -exp(c))-exp(c+d)*kb*tem*polylog(2, -exp(b-d))-exp(b)*kb*tem*polylog(2, -exp(c+enph/(kb*tem)))+exp(c+d)*kb*tem*polylog(2, -exp(b-d+enph/(kb*tem))))*enph*(kb*tem)^2/((exp(b)-exp(c+d))*kb*tem)+(exp(b)*enph^2*ln(1+exp(c+enph/(kb*tem)))-exp(c+d)*enph^2*ln(1+exp(b-d+enph/(kb*tem)))+2*exp(b)*enph*kb*tem*polylog(2, -exp(c+enph/(kb*tem)))-2*exp(c+d)*enph*kb*tem*polylog(2, -exp(b-d+enph/(kb*tem)))+2*exp(b)*kb^2*tem^2*polylog(3, -exp(c))-2*exp(c+d)*kb^2*tem^2*polylog(3, -exp(b-d))-2*exp(b)*kb^2*tem^2*polylog(3, -exp(c+enph/(kb*tem)))+2*exp(c+d)*kb^2*tem^2*polylog(3, -exp(b-d+enph/(kb*tem))))*(kb*tem)^3/((exp(b)-exp(c+d))*kb^2*tem^2))*bb+u*(1/(1+exp(-l-c))-1/((1+exp(-l-c))*(1+exp(l-b))))-(((1*enph)*(enph-2*kb*tem*ln(1+exp(-b+enph/(kb*tem))))/(2*kb^2*tem^2)+2*kb^2*tem^2*(-polylog(2, -exp(-b+enph/(kb*tem)))+polylog(2, -cosh(b)+sinh(b))))*enph*(kb*tem)^2-(enph^2*(enph-3*kb*tem*ln(1+exp(-b+enph/(kb*tem))))-6*kb^2*tem^2*(enph*polylog(2, -exp(-b+enph/(kb*tem)))+kb*tem*(-polylog(3, -exp(-b+enph/(kb*tem)))+polylog(3, -cosh(b)+sinh(b)))))*(kb*tem)^3/(3*kb^3*tem^3)-(-exp(b)*enph^2+exp(c+d)*enph^2-2*exp(c+d)*enph*kb*tem*ln(1+exp(-b+enph/(kb*tem)))+2*exp(b)*enph*kb*tem*ln(1+exp(-c-d+enph/(kb*tem)))+2*exp(c+d)*kb^2*tem^2*polylog(2, -exp(-b))-2*exp(b)*kb^2*tem^2*polylog(2, -exp(-c-d))-2*exp(c+d)*kb^2*tem^2*polylog(2, -exp(-b+enph/(kb*tem)))+2*exp(b)*kb^2*tem^2*polylog(2, -exp(-c-d+enph/(kb*tem))))*enph*(kb*tem)^2/((2*(-exp(b)+exp(c+d)))*kb^2*tem^2)-(exp(b)*enph^3-exp(c+d)*enph^3+3*exp(c+d)*enph^2*kb*tem*ln(1+exp(-b+enph/(kb*tem)))-3*exp(b)*enph^2*kb*tem*ln(1+exp(-c-d+enph/(kb*tem)))+6*exp(c+d)*enph*kb^2*tem^2*polylog(2, -exp(-b+enph/(kb*tem)))-6*exp(b)*enph*kb^2*tem^2*polylog(2, -exp(-c-d+enph/(kb*tem)))+6*exp(c+d)*kb^3*tem^3*polylog(3, -exp(-b))-6*exp(b)*kb^3*tem^3*polylog(3, -exp(-c-d))-6*exp(c+d)*kb^3*tem^3*polylog(3, -exp(-b+enph/(kb*tem)))+6*exp(b)*kb^3*tem^3*polylog(3, -exp(-c-d+enph/(kb*tem))))*(kb*tem)^3/((3*(-exp(b)+exp(c+d)))*kb^3*tem^3))*aa-u*(1/(1+exp(l-b))-1/((1+exp(-l-c))*(1+exp(l-b)))) = 0, -cc*polylog(2, -exp(b))+cc*polylog(2, -exp(-c))-impurity = 0])}, {op([b, c])})];

thank you.

## Error, too many levels of recursion...

“Error, too many levels of recursion” ,but there’s just a single expression.

How can this happen?

## Question on the function--unames()...

The function unames returns an expression sequence consisting of all the active names in the current Maple session which are ``unassigned names''.

But what unames() returns is obviously not the contents one expects:

## solving for listprocedure result of dsolve...

 (1)
 >

 >

 (2)
 >
 (3)
 >
 (4)
 >
 (5)
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 (6)
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i m calculating space of this elipse,i need to find point t1 wherein [XX(t1), YY(t1)] creates full circle and get S(t1). here its between 22.6-22.7. but i need to find it with ~0.1^3  accuracy.

for_clever_guys.mw

## How to make Maple18 return the accurate value?...

In the old version of Maple, the accurate value of Sin()and Cos() at some particular points, such as Pi/10, can be returned as below:

But in Maple 18, it just returns the same as the input.

How to make Maple18 return the accurate value as before?

## How to simplify this result from the ODE solver wi...

Here is the ODE:

dsolve((y(x)^2-x)*(D(y))(x)+x^2-y(x) = 0, {y(x)})

And the Maple 18 returns a very complex result.

But as we know,the more elegant result should be this:

How can I get this simple result with Maple?

## pointplot3d symbol=point .. no points...

with pointplot3d and 14,000 points when I enter symbol=point I get an empty plot.

Only when I set symbolsize=1 (a point) do I get points appearing in the graph.  Bug?

## Having Problems with dsolve - Error, unable to mat...

restart;
Eq1 := diff(T1(t), t) = (W*Cp*(To-T1(t))+UA*(Ts-T1(t)))/(M*Cp);
Eq2 := diff(T2(t), t) = (W*Cp*(T1(t)-T2(t))+UA*(Ts-T2(t)))/(M*Cp);
Eq3 := diff(T3(t), t) = (W*Cp*(T2(t)-T3(t))+UA*(Ts-T3(t)))/(M*Cp);
sys := Eq1, Eq2, Eq3;

Operational Veriables

W := 100;
UA := 10;
Cp := 2;
M := 1000;
To := 20;
Ts := 250;

Initial Conditions

sys1 := {Eq1, Eq2, Eq3};

nsys := nops(sys1);

ics := {T1(0) = 20, T2(0) = 20, T3(0) = 20};
{T1(0) = 20, T2(0) = 20, T3(0) = 20}
nics := nops(ics);
for i from 1 to nics do Sol ||i:=dsolve({sys1, ics[i]},{T1(t),T2(t),T3(t)},numeric)od;
Error, unable to match delimiters
Typesetting:-mambiguous(Typesetting:-mambiguous( for i from 1 to

nics do Sol verbarverbariAssigndsolvelpar(sys1comma ics(i))

commalcubT1(t)commaT2(t)commaT3(t)rcubcommanumericrparod,

Typesetting:-merror("unable to match delimiters")))

## mem usage maple.exe in task manager when high caus...

I was running some wav files through the spectrogram increasing the fft window size.  Generally just playing around.

I have run into an issue.  After running a few times the mem usage for maple.exe starts to run high.  I get it up to 600,000 K and still seems to run okay - ie able to produce a spectrogram.  However running it again at a higher window size of course eats up more memory and right around 1,000,000 K mem usage everything slows down and it appears to freeze.  The spectrogram is not displayed, after a short while CPU usage drops to zero the heartbeat circle (evaluating symbol - bottom left corner) stays solid and everything appears to stop.

It is possible to close the worksheet in the same maple session after some time and open a new one.

Another note.  After one worksheet has ramped up the mem usage to a large value say 800,000 K (it doesn't really matter) .. when I close the worksheet (in the same maple session) the mem usage remains high even after a restart;gc():   I not sure if this has been normal throughout the ages, but I thought after closing a high mem usage worksheet in the same maple session the mem usage in the windows task manager would have updated back down under 100,000 K at least.

The system Maple is running on right now is a P4 3Ghz Windows XP at 2.50 GB RAM Maple 18.00 stnd GUI 32 bit.  Using the spectrograms example in the application center for start.

Any insight as to why the computer starts to freeze up around 1,000,000 K mem usage would be helpful.  Also why closing a worksheet had no effect on the mem usage.  Would be interesting to know if this occurs on other machines as well.

## Another (maybe silly) question on a procedure...

As I stated in an earlier post, I'm new at this.

I'm trying to write a procedure to calculate what is called a "crescent latitude". The full formula can be seen here: https://db.tt/QAUzH5i0.

b is equal to 0.081819221; it takes a single parameter φ (latitude of a location in degrees)

I normally get errors like unable to parse, unable to match delimters, etc. and the result is the name of the procedure and whatevere value of the parameter I put in parenthesis, not the calculated value.

Anybody can help?

Thanlk you

Martina

## How do i obtain lie symmetries for this type of pa...

https://www.dropbox.com/s/r7xn2uqnn4qfbp7/Screenshot%202014-05-12%2015.21.07.png

## Units conversion problem...

This is an addition to the following post:

http://www.mapleprimes.com/questions/141795-Unit-Conversion-Problem

But I use the clickable facilities of Maple.  Here is the problem:

>32[[degC]];

32[[degC]]
right-click -> Units -> Replace units -> degF

288
--- [[degF]]
5

>evalf[5]( (2) );
57.600[[degF]]

but if I do that:

>convert(32, 'temperature', 'degC', 'degF');

448
---
5

>evalf[5]( (4) );
89.600

Why the conversion is bad when you try to do it by the clickable way????????????

```--------------------------------------
Mario Lemelin```
```Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## Why can't Maple solve this simple ODE??...

ode := diff(sqrt(U(t)), t) = sqrt(U__0)-sqrt(U(t))

ics := U(0) = 0

dsolve({ics, ode})

And the result maple returns is U(t)=0 !

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