## How can I use the values derived by fsolve in furt...

I have been using fsolve to derive constants for a polynomial. These are presented clearly in blue, but I am unable to reference these numbers for further calculations other than by typing them in manually. e.g. output is:

{d = 520.9032305, c = .41478630e-1, b = -.84548378e-5, a = .125070852e-8}

fsolve({y[1]=a*x[1]^3+b*x[1]^2+c*x[1]+d,y[2]=a*x[2]^3+b*x[2]^2+c*x[2]+d,
> y[3]=a*x[3]^3+b*x[3]^2+c*x[3]+d,y[4]=a*x[4]^3+b*x[4]^2+c*x[4]+d},{a,b,c,d});

## Warning, The use of global variables in numerical ...

Hi

I use dsolve( sys ode, ics)  and  dsolve( sys, ics, numeric) but both does not gives any solution of the system proposed.
May be I must fix some parameter or something else.

problemdisplaysolution.mw

many thinks

## Error, (in ExcelTools:-Export) while processing re...

Help create file Excel in ExcelTools, but error row 564?

thu_file.mw

## how to make power a vector?...

hi

i have a vector [V] and want to calculate f:=V^2;  and plot(V,f);how to do that?

i tried this but you can see in fig uploaded that an error occured.

## Error message in dsolve/numeric...

I want to solve the transient heat diffusion equation in a semi-infinite solid, both analyticall and numerically:

BVP1 := { diff( theta(eta), eta, eta) +2 * eta * diff(theta(eta), eta), theta(infinity) = 0, theta(0) = 1 };
Analytically:
sol1 := dsolve(BVP1);
theta(eta) = 1 - erf(eta)
which is the correct exact self-similar solution.
Numerically:
dsolve(BVP1, numeric) ;
and I got this error message:
Error, (in dsolve/numeric/bvp/convertsys) too few boundary conditions: expected 3, got 2
Why does Maple need three conditions and what is this extra condition?

## why this code don't work...

restart:with(geometry):with(plots):
> S:=segment:L:=line:Per:=PerpendicularLine:
> R:=5:xA:=0:yA:=0:point(A,xA,yA):xI:=R/3:yI:=0:point(I1,xI,yI):
> circle(C,[A,R]):

> local xM,yM,xN,yN,xE,yE,dr1:
> xM:=evalf(R*cos(t)):yM:=evalf(R*sin(t)):point(M,xM,yM):L(lMI,[M,I1]):
> intersection('h',C,lMI,[M,N]):L(lAM,[A,M]):L(lAN,[A,N]):
> Per(lME,M,lAM):Per(lNE,N,lAN):intersection(E,lME,lNE):
> S(sAM,[A,M]):S(sAN,[A,N]):S(sME,[M,E]):S(sNE,[N,E]):
> dr1:=draw({lMI(color=blue),sAM(color=black),sAN(color=black),
> sME,sNE}):
> display({dr1}):
> end:

> dr:=draw({C},view=[-6..17,-10..6]):

## How to resolve the problem??...

Hii,

I am using a command -NLPSolve(Ecost1, Q = 10 .. 20, initialpoint = {Q = 10}, assume = nonnegative, maximize = false). I am looking for solution that find the Q value at the minimum value of Ecost1. But Ecost1 should not go below 0.

and also I am getting an error -Warning, initialpoint option ignored by solver.

Kindly tell how to deal with these issues.

Thanks

## How to assign a sequence number once...

Hi， How can I  to assign a sequence number once. For example,

I want to ‘a0,a1,......an is assigned to variables x0 , x1,......, xn,’

I used command line as following ：

seq(x[i], i = 1 .. 5) := [1, 2, 3, 4, 5]，error as follows，‘Error, invalid left hand side in assignment’
Any  suggestion？

## Maple: How to solve the given Partial Differential...

I need help on solving the following PDE by Maple:

https://math.stackexchange.com/questions/3177491/how-to-solve-the-given-partial-differential-equation

## find second derivative value at turning point...

f :=2*sin(x^2/2)-sin(1*x/2)^2 In the interval [1,2] Find to the 10 significant figures the value of the second derivative at turning point

## Does additionally create new variables?...

Hi,
I'm very stunned by the results displayed in the worksheet below.
It seems that adding extra assumptions on a variable already constrained with "assume" has disturbing side effects ?

Here is a simplified worksheet that exhibits the phenomenon.
Basically I want to solve the equation a*x-b =b with respect to x.
In a first step I set assumptions on a and b and Maple returns x=0, as expected.
Next I add a new condition on b and ask Maple to solve the equation again. I intain this strange result: x=(b~ - b~)/a~.

Am I doing something wrong?

 > restart:
 > anames(user);
 > assume(a > 0): assume(b > 0):
 > f := a*x+b
 (1)
 > g := f=b: simplify(g); solve(g, a);
 (2)
 > anames(user);
 (3)
 > h := f=b: simplify(h); solve(h, a);
 > anames(user)  # additionally(b > a) doesn(t introduce a new variable
 (4)
 > indets(g); indets(h);  # why do I have b~ twice ?             # This is probably the reason why solve(h, a) doesn't work
 (5)
 > lprint(indets(h))
 {a, b, b, x}
 > # strange... solve(h, indets(h)[1]); simplify(%);
 (6)
 > # remark, dismantle explains nothing about the distinction between b~ and b~
 EQUATION(3)    POLY(6)       EXPSEQ(4)          NAME(4): a          NAME(4): b          NAME(4): x       DEGREES(HW): ^2 ^1 ^0 ^1       INTPOS(2): 1       DEGREES(HW): ^1 ^0 ^1 ^0       INTPOS(2): 1    NAME(4): b
 > dismantle(h)
 EQUATION(3)    POLY(6)       EXPSEQ(4)          NAME(4): a          NAME(4): b          NAME(4): x       DEGREES(HW): ^2 ^1 ^0 ^1       INTPOS(2): 1       DEGREES(HW): ^1 ^0 ^1 ^0       INTPOS(2): 1    NAME(4): b

 >

## How to force the binomial command to take into acc...

binomial(x, -1) should be 0 for any x which is not a negative integer.

When assuming x to be a positive integer, the command binomial indeed yields 0:

assume(x, posint); binomial(x, -1);

0

but when assuming x to be non-integer, the binomial command seems to ignore the assumption:

assume(x, Non(integer)); binomial(x, -1);
binomial(x, -1)

How to force the binomial command to take into account all assumptions?

## Maple Evaluation Time...

Hello,

I hope you are doing well. I have the followig equation which I want to solve w.r.t.o (x). Maple took more than 12 hours for evaulation and still no solution. What could be the reason? Could you please help.

(.5*(-sqrt(1/(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2)+1)+1/(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2)+1))/(2/(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2)+2)+(.5*(-sqrt(1/(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2)+1)+1/(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2)+1))/(2/(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2)+2) = (1/2)*sqrt(2)*(2*(-2^1.5*sqrt(.5*sqrt(2*(1-x))^2)/(2*sqrt(2*sqrt(2*(1-x))^2*.5+1))+sqrt(.5*sqrt(2*(1-x))^2)/(2*sqrt(.5*sqrt(2*(1-x))^2+1))+.5)-sqrt(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2)/(2*sqrt(2*(sqrt(2*x)+sqrt(2*(1-x)))^2*.5+1))-sqrt(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2)/(2*sqrt(.5*(sqrt(2*x)+sqrt(2*(1-x)))^2+1))-.5+sqrt(.5*(2*sqrt(2*x)+sqrt(2*(1-x)))^2)/(2*sqrt(2*(2*sqrt(2*x)+sqrt(2*(1-x)))^2*.5+1))+sqrt(.5*(2*sqrt(2*x)+sqrt(2*(1-x)))^2)/(2*sqrt(.5*(2*sqrt(2*x)+sqrt(2*(1-x)))^2+1))+.5+(sqrt(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2)/(2*sqrt(2*(sqrt(2*x)-sqrt(2*(1-x)))^2*.5+1))+sqrt(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2)/(2*sqrt(.5*(sqrt(2*x)-sqrt(2*(1-x)))^2+1))+.5)-sqrt(.5*(2*sqrt(2*x)-sqrt(2*(1-x)))^2)/(2*sqrt(2*(2*sqrt(2*x)-sqrt(2*(1-x)))^2*.5+1))-sqrt(.5*(2*sqrt(2*x)-sqrt(2*(1-x)))^2)/(2*sqrt(.5*(2*sqrt(2*x)-sqrt(2*(1-x)))^2+1))-.5)*c

## coordinate circle contact...

As a challenge problem.  At what x,y coordinate does circle B (radius r) make contact with circle A (radius R)?  Let's suppose the center of circle A is at (0,0).  The height circle B sits at, is d above the 0 x-axis.

## 3d plot spherical coordinates...

I'm trying to create an ellipsoid using spherical coordinates.

"x^2 + y^2/4 + z^2/9 = 1" how can I enter this?

This is what I have , but shape show up really crazy

plot3d([cos(theta)*sin(phi),sin(theta)*sin(phi),cos(phi)],theta=0..2*Pi,phi=0..Pi,scaling=constrained,axes=boxed);

Thanks

[An edited and reposted version of this Question, which has subsequently been deleted, specifically asked that the plot be done by making a small adjustment to Maple's spherical coordinates. The deleted version also named the ellipsoid E, a detail which is important for understanding correctly the OP's subsequent integration Question. --Carl Love acting as a Moderator]

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