Dear all,

I want to compute the charateristic polynomials of some matrices (the number of matrices is more than 10000), and write the coefficients of the resulting polynomials to a text file. The entries of the given matrices are stored in a text file. More specifically, suppose that M_1, M_2 and M_3 are three matrices, and the entries of them are stored in a text file named "data.txt" in the following form:

1 2 3

4 5 6

7 8 9

1 -1 0

2 3 6

-3 0 2

2 1 -1

1 -1 -2

0 1 2

The resulting output file should be of the following format:

1, -15, 18, 0

1, -6, 13, -28

1, -3, 1, 3

I don't know how to repeatedly read the data from the given text file. I think the procedure should be as follows.

>restart:

>with(LinearAlgebra):

>with(FileTools:-Text):

>fid:=Open("data.txt"):

>fid_1:=Open("data_1.txt"): #data_1 is the output file

>ReadFile(fid); #since the number of matrices is very large, I want the data to be read once

>numlines:=CountLines(fid);

>for i from 1 to numlines do

       here I need repeatedly read the data to a matrix M (I don't know how to do);

       P:=CharacteristicPolynomial(M,x);

       writedata[APPEND]("data_1.txt",map(i-> coeff(p, x, i), [seq(i, i = 0 .. degree(p, x))]));  #this statement cannot write the coefficients of a polynomial in the same row

>end do;

>Close(fid):

>Close(fid_1):

Now as I'm pretty new to Maple, I don't know any better and can't seem to get any information out of the help documents. 

Thanks a lot.

Hi,

So I wrote this script (30 lines) in Maple and it works fine. But now I want Maple to repeat the script while changing my input variable.

My variable is T and I want Maple to perform the script for T=0 to T=15 and with a step size of 0.1.

I tried for loop and proc, but could not make it work. What is the most appropriate way do this?

Thank you.

Hi everyone. Could I work with functions of complex variable in maple ?

Hi all,

I'm using MAPLE 13 and I'd like to know if someone knows how to generate the variables associated to the CodeGeneration for C code. At this moment I need to create manually the variable generated from the C code.

Example:

JJ := Jacobian(convert(Pint, Vector), [P1xenu, P1yenu, P1zenu, roll, pitch, yaw, D1xbody, D1ybody, P2xenu, P2yenu, P2zenu, ROLL, PITCH, YAW, D2xbody, D2ybody]);

CodeGeneration['C'](JJ, optimize);

Output:

t1 = cov2 * cov2;
t2 = cov1 * cov1;
t4 = 0.1e1 / (t1 + t2);
t5.......

And in the C code I need to create:

double t1, t2, t3..... manually

I can I solve this issue?

Best regards

André Dias

Hi everyone,

I have a question regarding the derivation of tensors/matrices.
Let's assume for simplicity, that I have a vector (6x1) s and a matrix A (6x6)defining Transpose(s)*Inverse(A)*s. From this function I want to calculate the derivative w.r.t. s. My approach would be

restartwith(Physics):
with(LinearAlgebra):
Define(s,A)

Diff(Transpose(s)*Inverse(A)*s, s)

As a result I get

though I'd rather expect something like Inverse(A)*s + Transpose(s)*Inverse(A)

Now as I'm pretty new to Maple, I can imagine that my approach is wrong, but I don't know any better and can't seem to get any information out of the help documents.

Thanks in advance for any of your suggestions!

Dear all,

It's very convenient to define a DE or PDE through Differential Operator D, for example,

((D[1, 1]+D[1, 2]+D[2, 2])(z))(x, y) = exp(x)*sin(y)

Is it possible to realize Inverse Operator Method of Operator D? How to solve the following equation if we rewrite the pde through inverse operator method?

(z)(x, y)=((D[1, 1]+D[1, 2]+D[2, 2])^(-1))exp(x)*sin(y)

Thanks a lot.

hi.i am a problem for solve analytic double integration as blow,plese help me....Thanks alot

int(int((2*gamma*cos(psi)/(D-r*sin(theta)*sin(phi))-2*gamma*cos(psi)/(D+r*sin(theta)*sin(phi)))*r^2*cos(theta)*sin(phi), r = 0 .. L), phi = 0 .. Pi)

I UPLOAD THIS INTEGRAL AS FOLLOW;;;;;int.mw

Download int.mw

I want to extract all the coefficients of a polynomial. For example, let p:=x^5-8x^3+2, and the function coeffs(p) returns 1, -8, 2. In fact, I want to obtain 1, 0, -8, 0, 0, 2. Thanks to everyone.

When I try to export my data from a spreadsheet to Excel, instead of numbers I get a long text containing numbers. For example instead of having just "11625.7677908435" I get "Typesetting:-mprintslash([11625.7677908435], [HFloat(11625.767790843516)])". 

How can I change the decimal to be displayed in the whole spreadsheet. The default decimals to be displayed is 4 in my version. How can I change it to another value? Also I don't want to click on "properties" each time I execute my worksheet. I want it to be automatically display  the number of digits I want. 

Hi,

I am connected to the linux version of Maple (xmaple) via putty and Xing (for GUI).

While the "big" code is running, I sometimes I got these messages,

But Maple (xmaple GUI) keeps running. It looks like it does not have an effect.

Should I be concerned?

How can I solve this problem on Maple?
Can anyone help me please ... I wrote another post before but I can not solve the problem.

lambda is an experimental parameter. I have this initial condition n(x,0)=0.4, c(x,0)=0.

Thanks to everyone

I want to get numerical solution of the Eqs.ode(see the folowlling ode and ibc）in Maple.However,when i run the following procedure,it prompts an error "Error, (in dsolve/numeric/bvp) cannot determine a suitable initial profile, please specify an approximate initial solution". How to solve the issue? Please help me.

restart:
n := 1.4; phi := 1; beta := .6931; psi := 1

> restart;
> n := 1.4; phi := 1; beta := .6931; psi := 1;

> s := proc (x) options operator, arrow; evalf(1+(phi*exp(beta*psi)*h(x))^n) end proc;

> Y := proc (x) options operator, arrow; evalf(f-(1/2-(1/2)/n)*ln(s(x))+2*ln(1-(1-s(x))^(-1+1/n))) end proc;

> ode := diff(h(x), `$`(x, 2))+(diff(Y(x), x))*(diff(h(x), x)+1) = 0;


> ibc := h(0) = 0, ((D(h))(10)+1)*s(10)^(-(1-1/n)*(1/2))*(1-(1-1/s(10))^(1-1/n))^2 = 0;

> p := dsolve({ibc, ode}, numeric);
Error, (in dsolve/numeric/bvp) cannot determine a suitable initial profile, please specify an approximate initial solution
>

I want to print the intersection of thie two circle but it shows

Error, (in plots:-display) expecting plot structure but received: `intersect`(CURVES([[1.000000000, 0.], [.9973715671, 0.4177774453e-1], [.9895277204, 0.8289662909e-1], [.9765921620, .1227081842], [.9587688933, .1605845580], [.9363389981, .1959284174], [.9096562091, .2281823686], [.8791413299, .2568377476], [.8452755984, .2814426418], [.8085930973, .3016090174], [.7696723313, .3170188388], [.7291271048, .3274290836], [.6875968398, .3326755761], [.6457364935, .3326755761], [.6042062285, .3274290835], [.5636610020, .3170188387], [.5247402363, .3016090175], [.4880577352, .2814426419], [.4541920036, .2568377477], [.4236771240, .2281823683], [.39...
How can i do for this problem to solve

At the moment, I am using

>writeto("Result1.txt");

> printf(StringTools[FormatTime]("%c\n"));
Thu Jul 31 14:28:08 2014

# lots of things here

# lots of things here

# lots of things here

>writeto(terminal);

To write a time and date stamp into my result1.txt file.

I understand that I can't write : into file names, but is there a way to writeto file using a more informative file name with date and time, such as,

Result_Thu Jul 31 14-28-08 2014.txt

Is that something can be easily formatted?

casper