# Solve the equation for x

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hassan tahir on 25 Nov 2020
Commented: hassan tahir on 25 Nov 2020
I am trying to solve this equation, but Matlab keep showing error in the equation.
please guide me, where am I making mistake?
syms x
p = 0.89;
a = 6.7;
v = 26.12;
r = 0.07;
L = 78.05;
s = 34.01;
n = 0.33;
m = 0.5;
w = 22.49;
b = -0.06;
T = 50;
fun = p.* exp.^(-exp.^((v-x)./a)) + r.* exp.^(-((x-m)./s).^(-L)) +(1-p-r).*exp((-(1+b.*((x-w)./n))).^(-1./b))-(1-1./T) ==0;
sol = solve(fun,x)

Stephan on 25 Nov 2020
How is it different to your other question?
hassan tahir on 25 Nov 2020
that equation was the mixed equation of PDF and this equation is a mixed equation of CDF. I kind a took integration.
Is it possible to solve this equation?

KSSV on 25 Nov 2020
Edited: KSSV on 25 Nov 2020
Repalce
exp.^()
with smply:
exp()
Also element by element operation not reuqired:
fun = p* exp(-exp((v-x)/a)) + r* exp(-((x-m)/s)^(-L)) +(1-p-r)*exp((-(1+b*((x-w)/n)))^(-1./b))-(1-1/T) ==0;

#### 1 Comment

hassan tahir on 25 Nov 2020
thank you so much, equation problem solved but still showing error in sol = solve(fun,x)

Stephan on 25 Nov 2020
Make the changes suggested in the answer from KSSV and use vpasolve:
syms x
p = 0.89;
a = 6.7;
v = 26.12;
r = 0.07;
L = 78.05;
s = 34.01;
n = 0.33;
m = 0.5;
w = 22.49;
b = -0.06;
T = 50;
fun = p.* exp(-exp((v-x)./a)) + r.* exp(-((x-m)./s).^(-L)) +(1-p-r).*exp((-(1+b.*((x-w)./n))).^(-1./b))-(1-1./T) ==0;
sol = vpasolve(fun,x)
gives:
sol =
33.743940154221419170734691781397

#### 1 Comment

hassan tahir on 25 Nov 2020
really appreciated!!
Basically, this is return period equation. as I change the T values e.g (10,50,100,200), it should gives me different values. but If I put T<72, the answer comes in iota 'i' form.
any idea or suggestion?