mehdi jafari

Ask a Question

Create a Post

13 Badges

Member for: 11 years, 236 days

Contact mehdi jafari

MaplePrimes Activity

These are questions asked by mehdi jafari

a question on integration of error funct...

Asked: mehdi jafari 769 Product: Maple

August 07 2019

1 0

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-b1x)^2/(2sigma^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

a problem with fsolve...

Asked: mehdi jafari 769 Product: Maple

July 07 2019

2 0

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-HHDD));

(1)

>	EQ:=F-E*Y;

(2)

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

(3)

(4)

>	fsolve(EQ)

(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)

(7)

Download fsolve.mw

A problem related to chain rule derivati...

Asked: mehdi jafari 769 Product: Maple

June 21 2019

2 5

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

Linear composition of vectors...

Asked: mehdi jafari 769 Product: Maple

February 22 2019

2 1

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.

problem in dsolve...

Asked: mehdi jafari 769 Product: Maple 2018

January 15 2019

1 0

i have two ode equations, when try to solve, i face this error
Error, (in dsolve/numeric/bvp/convertsys) unable to convert to an explicit first-order system
any comment or help to solve this? ( or any simplifying comments to solve) . thnx in advance

restart

>	A := 4263736263.736263:B := 11868131.86813187:C := 600146.5201465202:hr := 0.3e7:muz := 0.2632654643708247e-5:P:=1000:

(1)

>	ode1 := diff(u(r), r, r)+(diff(u(r), r))/r-u(r)/r^2-B*(diff(w(r), r, r, r)+(diff(w(r), r, r))/r-(diff(w(r), r))/r^2)/A = 0;

diff(diff(u(r), r), r)+(diff(u(r), r))/r-u(r)/r^2-0.2783505155e-2*(diff(diff(diff(w(r), r), r), r))-0.2783505155e-2*(diff(diff(w(r), r), r))/r+0.2783505155e-2*(diff(w(r), r))/r^2 = 0

(2)

>	ode2 := C(diff(w(r), r, r, r, r))+2C(diff(w(r), r, r, r))/r-(C/r^2+muzhr^2)(diff(w(r), r, r))+(C/r^3-muzhr^2/r)(diff(w(r), r))+muzhr^2w(r)/r^2-B(diff(u(r), r, r, r))-2B(diff(u(r), r, r))/r+B(diff(u(r), r))/r^2-Bu(r)/r^3 = P;