mehdi jafari

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6 years, 118 days

MaplePrimes Activity


These are questions asked by mehdi jafari

i have a question about sets. how can i keep set members in order of addition not the defualt maple ordering.
in maple help, i saw the command setsort=0..8 but i do not know how to use it.
consider exmaple below:


 

restart

L:={}:

for j in [3,5,6,1] do
birth:=j:
L:=`union`(L ,{j});
od;

3

 

{3}

 

5

 

{3, 5}

 

6

 

{3, 5, 6}

 

1

 

{1, 3, 5, 6}

(1)

 


how can i keep L as order of addition? L={3,5,6,1}. thanks in advance

Download setoder.mw

how this integral can be calculated in the simplest form ? the second question is what exactly is done when using assuming? for example when using assuming real, all the functions or parameteres are affected? thanks in advanced

 

restart:with(IntegrationTools):

(int(int(exp(-(y-beta[0]-beta[1]*x-b0-b1*x)^2/(2*sigma^2))*exp(-b0)*exp(-b1),b0=0..infinity),b1=0..infinity,continuous=true) assuming real)

signum(limit(-(1/2)*Pi^(1/2)*exp((1/2)*(2*b1+2*beta[1])*x+(1/2)*sigma^2-y-b1+beta[0])*2^(1/2)*sigma*(erf((1/2)*(sigma^2+(b1+beta[1])*x-y+beta[0])*2^(1/2)/sigma)-signum(sigma)), b1 = infinity))*infinity

(1)

 


 

Download error_function.mw

i have a problem with a nonlinear equation containing Heaviside step function. fsolve does not return anything and SolveEquation command also returns incorrect answer. How can i solve this equation? any method or help is appreciated.


 

 

restart:

with(DirectSearch):

F:=x*(Heaviside(x-(S0))/(1-DD)+Heaviside(-x+S0)/(1-HH*DD));

x*(Heaviside(x-S0)/(1-DD)+Heaviside(-x+S0)/(-DD*HH+1))

(1)

EQ:=F-E*Y;

-E*Y+x*(Heaviside(x-S0)/(1-DD)+Heaviside(-x+S0)/(-DD*HH+1))

(2)

HH:=0.2;
DD:=0.579350262599427;
S0:=1e8;
E:=70e9;
Y:=0.001668993263529;

.2

 

.579350262599427

 

0.1e9

 

0.70e11

 

0.1668993263529e-2

(3)

EQ

-116829528.5+x*(2.377274752*Heaviside(x-0.1e9)+1.131055455*Heaviside(-x+0.1e9))

(4)

fsolve(EQ)

fsolve(-116829528.5+x*(2.377274752*Heaviside(x-0.1e9)+1.131055455*Heaviside(-x+0.1e9)), x)

(5)

SolveEquations(EQ)

Warning, complex or non-numeric value encountered; trying to find a feasible point

 

[1.3868049384289111*10^13, Vector(1, {(1) = -3723983.000}), [x = 9.999999999999999*10^7], 231]

(6)

eval(EQ,x = 1.00000000000000*10^8)

Float(undefined)

(7)

 


 

Download fsolve.mw

i have two expressions. S1 and S2 are functions of sigma and tau. but i need derivative of sigma and tau with respect to S1 and S2. what should i do ? could any one help?


 

restart

S1 := -4*sqrt(sigma1^2 + 4*tau^2)*tau^2/((sigma1 + sqrt(sigma1^2 + 4*tau^2))^2*(1 + 4*abs(tau/(sigma1 + sqrt(sigma1^2 + 4*tau^2)))^2))

-4*(sigma1^2+4*tau^2)^(1/2)*tau^2/((sigma1+(sigma1^2+4*tau^2)^(1/2))^2*(1+4*abs(tau/(sigma1+(sigma1^2+4*tau^2)^(1/2)))^2))

(1)

S2 := 4*sqrt(sigma1^2 + 4*tau^2)*tau^2/((-sigma1 + sqrt(sigma1^2 + 4*tau^2))^2*(1 + 4*abs(tau/(-sigma1 + sqrt(sigma1^2 + 4*tau^2)))^2))

4*(sigma1^2+4*tau^2)^(1/2)*tau^2/((-sigma1+(sigma1^2+4*tau^2)^(1/2))^2*(1+4*abs(tau/(-sigma1+(sigma1^2+4*tau^2)^(1/2)))^2))

(2)

 

 

 


 

Download chain_rule_derivative.mw

Hi. how can maple determine whether a vector is linear compostion of two or more vectors? 
for example w=a*v+b*u so that w is linear compostion of vectors u and v ( a and b are scalar numbers). tnx for the help.

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