Hi Guys. I´ve got a problem with the mod (mods,modp) function of maple.

I want to calculate the following congruences:

mod(4,-5) = -1 BUT maple returns 4

mod(-3,-4)=-3 but maple returns 1

and so on....

Does anybody of you know how to fix this? thanks!

Hello,

I have a problem. I want to make plot 3d for pressure drop in diffuser by posuille formula,

but with increasing of "l"(length of channel) graph shows wrong pressure drop. Normally with i increasing of "L" we should have...

> restart; R := 8.314;print(??); # input placeholder> G1[1] := piecewise(`and`(T > 298, T < 700), -7976.15+137.093038*T-24.3671976*T*log(T)-0.1884662e-2*T^2-0.877664e-6*T^3+74092/T, `and`(T >= 700, T < 933), -11276.24+223.048446*T-38.5844296*T*log(T)+0.18531982e-1*T^2-0.5764227e-5*T^3+74092/T, `and`(T >= 933, T < 2900), -11278.361+188.684136*T-31.748192*T*log(T)-0.1230622e29/T^9, 0);print(??); # input placeholder

> G1[2] := piecewise(`and`(T > 298, T < 700...

The system consists of 3 equationsHow can you single out one of the solutions in obtaining module and plot for it?
a := 1; m := 1/64 
l1 := 2*(diff(ur(e, t), t))+(1+tanh((1/20)*e))*(diff(ui(e, t), `$`(e, 2)))+2*a*(ui(e, t)*ur(e, t)*ur(e, t)+(ui(e, t)*ui(e, t))*ui(e, t))+m*ui(e, t)*(diff(ur(e, t)^2, e))+m*ui(e, t)*(diff(ui(e, t)*ui(e, t), e)) = 0 
l2 := -2*(diff(ui(e, t), t))+(1+tanh((1/20)*e))*(diff(ur(e, t), `$`(e, 2)))+2*a*(ur(e, t...

Let say that you have two datasets:

restart:
with(MyFinance):
z1 := GetCSV("http://www.quandl.com/api/v1/datasets/USER_18Q/18R.csv?&auth_token=BXckVSG3twWkV272c9Q4&trim_start=1968-04-01&trim_end=2013-04-12&collapse=daily&transformation=rdiff&sort_order=desc");
z2 := GetCSV("http://www.quandl.com/api/v1/datasets/USER_18Q/1EV.csv?&auth_token=BXckVSG3twWkV272c9Q4&trim_start=1994-01-03&trim_end=2013-04-12&collapse=daily&...

** comparison link has been updated for Maple 2015 **  All three M's have identical speed performances

Someone has created a comparison of Mathermatica 9, Maple 17 and Matlab 2013a here http://12000.org/my_notes/rankTest/test.htm

The timings and codes used were as follows:

2.2.1 Mathematica

Remove["Global‘*"];  
Share[];  
n = 7000;  
m = Table[Random[], {i, 1, n}, {j, 1, n}];  
AbsoluteTiming[MatrixRank[m];]


2.2.2 Maple

restart;  
kernelopts(gcfreq= 2^22):  
UseHardwareFloats:= true:  
gc():  
 
n:=7000:  
 
M:= LinearAlgebra:-RandomMatrix(  
     n  
    ,n  
    ,generator=0.0 .. 1  
    ,outputoptions=[datatype=float[8]]  
):  
 
time[real](LinearAlgebra:-LA_Main:-Rank(M));



2.2.3 Matlab

clear all;  
n=2500;  
A=rand(n,n);  
tic();  
rank(A);  
toc()

Certainly that must be the slowest possible route for Maple ever.  Anyone care to post their code and timings?

Maple gives the fourier transformation:

fourier(int(y^k*exp(-k*x*y/phi+I*y*omega), y = 0 .. infinity), omega, t) as:

2*Pi*t^k*exp(-t*k*x/phi)*piecewise(t < 0, 0, 1)+piecewise(0 < t, -2*Pi*t^k*exp(-t*k*x/phi), 0)

but it is identically 0.

if change the order of integration and integate exp(I*y*omega) first, the transform is equal to

int(Dirac(y-t)*y^k*exp(-k*x*y/phi), y = 0 .. infinity)

which is Heaviside(t)*t^k*exp(-t*k*x/phi)

When I solve a systems of equations, fsolve gives the solution

.

I now want want to define the variables x, y and z as respectively 5, 6 and 1 - but without copying the solution. Because this is a solution that I get in a loop, so it changes in every step. Maybe there is a easy way to put it in a vector?

I often have large matrices and have to grab only every nth column or row (for plotting

for example). So far I've been doing it this way:

nthColumns:=proc(v_m, v_n)  

v_m[..,[seq(i, i=1..rtable_size(v_m)[2], v_n)]]

end;

nthRows:=proc(v_m, v_n) 

 v_m[[seq(i, i=1..rtable_size(v_m)[1], v_n)],..]

end;

A := LinearAlgebra:-RandomMatrix(20, 20, outputoptions = [datatype = float[8]]);

I only want to display 'position' in animation while tend <= 12:
This is the trial:

restart:with(plots):
for tend from 0 to 50
while (tend <= 12) do
pos:=animate(textplot3d,[[-1.8,0,alpha*tend, 'position']], tend=0..50,frames=150);
od;
display(pos);

I receive error messages:
error, (in plots/animate) 0=0..50 is an invalid animation range

Then I try:

restart:with(plots):
while (tend <= 12) do

Helo every one,

I'm trying to find the positive real root from:

and substitute it in:

my prog is:

eq5:=u->-3*b*k*u^2-3*b*k^2*u^4-k^3*u^6*b+k*u+5*k^2*u^3-b:  

                   (solve(eq5(u),u)): S:=array([...

I am using Maple 15 and every time I try to plot this equation it doesnt seem to want to plot. This is the code I keep trying to input:

plot(3*e^(-x)*x-e^(-x)-1.5*e^(-x)*(x^2)+e^(-x)*(x^2)*log(x),x=0..9,y=-1..0.6);

Every time I get "Plotting Error, empty plot"

The equation came from the original differential equation .5(d^2y/dx^2)+(dy/dx)+.5y(x)=ln(x)e^(-x)

 Also When i try to plot this equation:

-.5*e^(-10*x)*sin(10*x)-.5*e^(-10*x)*cos(10*x)+(3/2)=300

Solve for x in the following expression.

log x=-4

Hi!

I just got a simple expression after a longer equation where the last number in the expression is very small, and should be se seen as zero.

E[A]+40,0*10^-9, and it should only say E[A]

Is there a simple command to "round away" 40*10^-9?

It has to be simple because it is written in a report.

Best Regards

 Nicolai

hi friends i have already asked help related to this code which am gona post but this time I am facing some different problem. In the worksheet which i attached below is having algorthim for cubic spline on heat equation. IN this sheet FD equation is my main equation and i want this equation to use boundary conditions mention in code. After using that i want this equation to generate system of linear equations when i=0..M, j=1..N. But i dont want to solve it completely. After...