Is it possible to convert E1(x) to Ei(x) explicitly?

In particular I have this expression which is real, but imaginary numbers appear due to the definition of Ei1 for negative arguments.

(-exp(j*z)*Ei(1, j*z)+I*Pi*exp(-j*z)+exp(-j*z)*Ei(1, -j*z))/(2*j)

j>0,z>0

Thank you

In the application whose link is below, an error message results when I right click the fsolve command and select explore.

https://www.maplesoft.com/applications/view.aspx?SID=119851

I would like to explore changes to several of the parameters in the equations named "sys", especially the value of Qoutflow. Can this be done and, If so, how can the solved values, Q1, Q2, Q3, and H be graphed as the slider values of individual parameters values are modified?

1) How can i get the event time. This example 0.69313.

2) I don't want to see the Warning.How can i do it? 

Warning, cannot evaluate the solution further right of .69314729, event #1 triggered a halt

how i can dsolve this equations and  convert the equations to an explicit first-order system ?

Also parameter 'p' is unknown and shoud be found.

Error, (in dsolve/numeric/bvp/convertsys) unable to convert to an explicit first-order system
error2.mw

Download error2.mw

The procedure F computes the smallest prime factor of  ithprime(n)-2

F := n -> ifactors((ithprime(n)-2))[2][1][1]:

F(11);
                               29
Strangely, print(F)  must be interrupted!
print(F);
Warning,  computation interrupted
 
Also,

F := n -> ifactors((ithprime(n)-2))[2][1][1];

Warning,  computation interrupted
Warning,  computation interrupted

(F is defined, only the display fails).
This happens only for interface(typesetting=extended).
In Maple 2017 it was OK.

how I can remove this error.

Error, numeric exception: division by zero

code2.mw

Hello,

      I was trying to apply some assumptions to a pdsolve command and noticed a strange error. Here's a minimal working example.

restart():

pdsolve(diff(f(t,x),t) = 0, {f(t,x)}, ivars = {x, t}) assuming x::real:

returns

Error, (in simpl/relopsum) invalid terms in sum: diff(f(t,x),t) = 0

Is this indeed a bug, or is it expected behavior?

Hello I don't mean this to the discredit of any others, and attempted to use the "contact user" feature, but the emails bounced, anyway I was hoping to get the user @Carl Love or @acer to assist me with this subject https://math.stackexchange.com/questions/2814343/finding-a-better-approximation-to-a-prime-number-relation

with(numtheory):

q := proc (h) options operator, arrow; min(`minus`(divisors(h*floor(ithprime(h)/h)), {1})) end proc;

DATA := [seq([h, simplify((h*igcd(h, h*q(h))-floor(sqrt(h))*igcd(floor(sqrt(h)), q(h)))^(1/2), 'radical')], h = 1 .. 300)];

plots[:-pointplot](DATA, color = "Black");
 

I was using the following idea to get the computation time of my computations in Maple;

s:=time():
my computation
print(time()-s);

But it seems if I use

Grid:-Map(m->My computation(m),[some sequence]);

Where the sequence has more than one element, this idea doesn't work! It seems Maple time() remains fixed during this Grid:-Map when the sequence has more than one element. So then how should I check the computation time?

In the following pictures you can see when the sequence has one element, it works normal, but when it has two elements, it doesn't work the same.

What is the best way to solve the coupled differential equation sets (like below) in Maple?

Letter_M.mwsLetter_M.txt

Attached are two similar files: one written in Maple 7 code, and a similar text file.

    My original intention was to have the two dimensional letter M do an animated "knees up" in just one color.  However the program works - but not as I intended.  The individual four sections danced around - and I thought it was rather novel - but decided to make each one a different color - red, blue, white and turquoise.  I was surprised to find the polygons were all the same turquise color - that of the fourth polygon.   Is there an easy fix, or must I write four separate procs for the four polygons?

Thanks in advance for any advice.  David 

I am attempting to reproduce the results claimed by analog.com for a band pass filter.

I have checked the circuit specification and found no errors.

Am I expecting too much or am I doing something wrong?

## www.analog.com/designtools/en/filterwizard/
## Filter Requirements for Band-Pass, 4th order Butterworth
## Specifications: Optimize for Power, +Vs= 5, -Vs= -5
## Gain: 10 dB
## Passband: -3dB at 2kHz
## Stopband: -40dB at 40kHz
## Component Tolerances: Capacitor = 5%; Resistor = 1%; Inductor = 5%; Op Amp GBW = 20%

restart;
with(Syrup); Version;
with(DynamicSystems):

ckt := "*60 kHz Band Pass Filter  \n\
vin 1   0 \n\
R1A 1   2 165k \n\
R1B 5   7 169k \n\
R2A 2   0 976 \n\
R2B 7   0 1k \n\
R3A 6   0 221 \n\
R3B 11  0 226 \n\
R4A 5   6 12.7k \n\
R4B 10 11 12.7k \n\
R5A 4   3 97.6k \n\
R5B 9   8 100k \n\
R98 3   0 1e9 \n\
R99 8   0 1e9 \n\
C1A 2   4 270pF \n\
C1B 7   9 270pF \n\
C2A 2   3 270pF \n\
C2B 7   8 270pF \n\
* \n\
X1A 6  3 5  NonIdealOpAmp \n\
X1B 11 8 10 NonIdealOpAmp \n\
.include Library:-NonIdealOpAmp \n\
.end";

volts, others := Solve(ckt, 'ac', 'returnall');
gain := eval(v[10]/vin, volts);
H := subs({A=80000, f0=15*10^6, Ro=100}, gain);
evalf(H);
tf := evalf(H);
sys := TransferFunction(tf);
PrintSystem(sys);
plotsetup(maplet);
MagnitudePlot(sys);

please see maple attachment below.

btw, what i'm really trying to do is represent spin 1/2 states, along with the usual spin operators, and be able to take tensor products of the spin states. any hints on how to do that would be greatly appreciated. 

btw, the physics package is amazing! 

thanks, 

larry

bug.mw

Hello

I have a problem with "Infinitesimals" for the system of equations. 

"Infinitesimals" Counts the system for (x, t) but shows an empty string for (x, y, z, t).

When I add to the equation (img 2) u [y, y], u [z, z] or simply y ^ 2, z ^ 2, Maple shows an empty string in Infinitesimal.

Thank you in advance.

Hi everybody, 

Here is a piece of a more important worksheet where I need to push the number of Digits farther (Digits:=30:) than the default value.
Nevertheless I don't want to be annoyed by excessively lengthy outputs and I use interface(displayprecision=6).

It seems that the result of an operation which contains only floats is a 6 digits precision number but, as soon as the same operation contains an integer, the displayed precision equals the value of Digits  ???
To be honnest, simpler situations do not exhibit the behaviour shown in the attached file.

Can anyone explain me why I get tho wifferent displays for the quantity names xi__d ? 

As always, great thanks in advance

displayprecision.mw

PS : I use Maple 2015.2 on Mac OSX El Capitan