Solve a system of equations with $exp$ function
$begingroup$
I would like your help to understand whether the following system admits a unique solution for the unknowns $rho_1, rho_2, rho_0$.
$$
begin{cases}
1-t=frac{exp { rho_0+rho_1+ rho_2(1)}}{1+exp { rho_0+rho_1+ rho_2}}\
r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}
\
w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}
end{cases}
$$
$r,t,w$ are known values in $(0,1)$.
Here my incomplete attempt to simplify:
$$
begin{cases}
log(1-t)=rho_0+rho_1+ rho_2-log(1+exp { rho_0+rho_1+ rho_2})\
log(r)= rho_0+ rho_2 -log(1+exp{ rho_0+ rho_2})
\
log(w)=-log(1+exp { rho_0+rho_1+ 2rho_2})
end{cases}
$$
I'm unable to proceed.
logarithms exponential-function systems-of-equations
$endgroup$
add a comment |
$begingroup$
I would like your help to understand whether the following system admits a unique solution for the unknowns $rho_1, rho_2, rho_0$.
$$
begin{cases}
1-t=frac{exp { rho_0+rho_1+ rho_2(1)}}{1+exp { rho_0+rho_1+ rho_2}}\
r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}
\
w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}
end{cases}
$$
$r,t,w$ are known values in $(0,1)$.
Here my incomplete attempt to simplify:
$$
begin{cases}
log(1-t)=rho_0+rho_1+ rho_2-log(1+exp { rho_0+rho_1+ rho_2})\
log(r)= rho_0+ rho_2 -log(1+exp{ rho_0+ rho_2})
\
log(w)=-log(1+exp { rho_0+rho_1+ 2rho_2})
end{cases}
$$
I'm unable to proceed.
logarithms exponential-function systems-of-equations
$endgroup$
$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54
add a comment |
$begingroup$
I would like your help to understand whether the following system admits a unique solution for the unknowns $rho_1, rho_2, rho_0$.
$$
begin{cases}
1-t=frac{exp { rho_0+rho_1+ rho_2(1)}}{1+exp { rho_0+rho_1+ rho_2}}\
r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}
\
w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}
end{cases}
$$
$r,t,w$ are known values in $(0,1)$.
Here my incomplete attempt to simplify:
$$
begin{cases}
log(1-t)=rho_0+rho_1+ rho_2-log(1+exp { rho_0+rho_1+ rho_2})\
log(r)= rho_0+ rho_2 -log(1+exp{ rho_0+ rho_2})
\
log(w)=-log(1+exp { rho_0+rho_1+ 2rho_2})
end{cases}
$$
I'm unable to proceed.
logarithms exponential-function systems-of-equations
$endgroup$
I would like your help to understand whether the following system admits a unique solution for the unknowns $rho_1, rho_2, rho_0$.
$$
begin{cases}
1-t=frac{exp { rho_0+rho_1+ rho_2(1)}}{1+exp { rho_0+rho_1+ rho_2}}\
r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}
\
w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}
end{cases}
$$
$r,t,w$ are known values in $(0,1)$.
Here my incomplete attempt to simplify:
$$
begin{cases}
log(1-t)=rho_0+rho_1+ rho_2-log(1+exp { rho_0+rho_1+ rho_2})\
log(r)= rho_0+ rho_2 -log(1+exp{ rho_0+ rho_2})
\
log(w)=-log(1+exp { rho_0+rho_1+ 2rho_2})
end{cases}
$$
I'm unable to proceed.
logarithms exponential-function systems-of-equations
logarithms exponential-function systems-of-equations
asked Dec 18 '18 at 12:33
STFSTF
691422
691422
$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54
add a comment |
$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54
$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54
$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
$displaystyle r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}impliesexp{ rho_0+ rho_2}=frac r{1-r}$
$displaystyle1-t=frac{exp { rho_0+rho_1+ rho_2}}{1+exp { rho_0+rho_1+ rho_2}}=frac{rexp{{rho_1}}}{1-r+rexp {rho_1}}impliesexp{{rho_1}}=frac{(1-r)(1-t)}{rt}$
$displaystyle w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}=frac{1}{1+exp { rho_2}cdotfrac r{1-r}cdotfrac{(1-r)(1-t)}{rt}}implies exp{{rho_2}}=frac{t(1-w)}{w(1-t)}$
$$thereforedisplaystylerho_0=lnBig[frac{rw(1-t)}{t(1-r)(1-w)}Big]$$
$$displaystylerho_1=lnBig[frac{(1-r)(1-t)}{rt}Big]$$
$$displaystylerho_2=lnBig[frac{t(1-w)}{w(1-t)}Big]$$
$endgroup$
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
add a comment |
Your Answer
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
$displaystyle r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}impliesexp{ rho_0+ rho_2}=frac r{1-r}$
$displaystyle1-t=frac{exp { rho_0+rho_1+ rho_2}}{1+exp { rho_0+rho_1+ rho_2}}=frac{rexp{{rho_1}}}{1-r+rexp {rho_1}}impliesexp{{rho_1}}=frac{(1-r)(1-t)}{rt}$
$displaystyle w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}=frac{1}{1+exp { rho_2}cdotfrac r{1-r}cdotfrac{(1-r)(1-t)}{rt}}implies exp{{rho_2}}=frac{t(1-w)}{w(1-t)}$
$$thereforedisplaystylerho_0=lnBig[frac{rw(1-t)}{t(1-r)(1-w)}Big]$$
$$displaystylerho_1=lnBig[frac{(1-r)(1-t)}{rt}Big]$$
$$displaystylerho_2=lnBig[frac{t(1-w)}{w(1-t)}Big]$$
$endgroup$
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
add a comment |
$begingroup$
$displaystyle r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}impliesexp{ rho_0+ rho_2}=frac r{1-r}$
$displaystyle1-t=frac{exp { rho_0+rho_1+ rho_2}}{1+exp { rho_0+rho_1+ rho_2}}=frac{rexp{{rho_1}}}{1-r+rexp {rho_1}}impliesexp{{rho_1}}=frac{(1-r)(1-t)}{rt}$
$displaystyle w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}=frac{1}{1+exp { rho_2}cdotfrac r{1-r}cdotfrac{(1-r)(1-t)}{rt}}implies exp{{rho_2}}=frac{t(1-w)}{w(1-t)}$
$$thereforedisplaystylerho_0=lnBig[frac{rw(1-t)}{t(1-r)(1-w)}Big]$$
$$displaystylerho_1=lnBig[frac{(1-r)(1-t)}{rt}Big]$$
$$displaystylerho_2=lnBig[frac{t(1-w)}{w(1-t)}Big]$$
$endgroup$
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
add a comment |
$begingroup$
$displaystyle r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}impliesexp{ rho_0+ rho_2}=frac r{1-r}$
$displaystyle1-t=frac{exp { rho_0+rho_1+ rho_2}}{1+exp { rho_0+rho_1+ rho_2}}=frac{rexp{{rho_1}}}{1-r+rexp {rho_1}}impliesexp{{rho_1}}=frac{(1-r)(1-t)}{rt}$
$displaystyle w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}=frac{1}{1+exp { rho_2}cdotfrac r{1-r}cdotfrac{(1-r)(1-t)}{rt}}implies exp{{rho_2}}=frac{t(1-w)}{w(1-t)}$
$$thereforedisplaystylerho_0=lnBig[frac{rw(1-t)}{t(1-r)(1-w)}Big]$$
$$displaystylerho_1=lnBig[frac{(1-r)(1-t)}{rt}Big]$$
$$displaystylerho_2=lnBig[frac{t(1-w)}{w(1-t)}Big]$$
$endgroup$
$displaystyle r=frac{exp { rho_0+ rho_2 }}{1+exp{ rho_0+ rho_2}}impliesexp{ rho_0+ rho_2}=frac r{1-r}$
$displaystyle1-t=frac{exp { rho_0+rho_1+ rho_2}}{1+exp { rho_0+rho_1+ rho_2}}=frac{rexp{{rho_1}}}{1-r+rexp {rho_1}}impliesexp{{rho_1}}=frac{(1-r)(1-t)}{rt}$
$displaystyle w=frac{1}{1+exp { rho_0+rho_1+ 2rho_2}}=frac{1}{1+exp { rho_2}cdotfrac r{1-r}cdotfrac{(1-r)(1-t)}{rt}}implies exp{{rho_2}}=frac{t(1-w)}{w(1-t)}$
$$thereforedisplaystylerho_0=lnBig[frac{rw(1-t)}{t(1-r)(1-w)}Big]$$
$$displaystylerho_1=lnBig[frac{(1-r)(1-t)}{rt}Big]$$
$$displaystylerho_2=lnBig[frac{t(1-w)}{w(1-t)}Big]$$
answered Dec 18 '18 at 12:53
Shubham JohriShubham Johri
5,427818
5,427818
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
add a comment |
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Thanks: I think $2$ in front of $rho_2$ has been ignored in your derivations.
$endgroup$
– STF
Dec 18 '18 at 13:16
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Where exactly did I miss it?
$endgroup$
– Shubham Johri
Dec 18 '18 at 14:40
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
Sorry: am I right that in the second equality for $w$ we should have $frac{1}{1+exp{2rho_2}frac{r}{1-r} frac{(1-r)(1-t)}{rt}}$?
$endgroup$
– STF
Dec 18 '18 at 15:06
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
$exp{{rho_1+rho_1+2rho_2}}=exp{{rho_0+rho_1+rho_2}}cdotexp{{rho_2}}=frac{1-t}tcdotexp{{rho_2}}$. I got $exp{{rho_0+rho_1+rho_2}}$ by multiplying the expressions for $exp{{rho_0+rho_2}}$ and $exp{{rho_1}}$
$endgroup$
– Shubham Johri
Dec 18 '18 at 15:09
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
$begingroup$
I see now. Thanks
$endgroup$
– STF
Dec 18 '18 at 15:19
add a comment |
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$begingroup$
Solve for $exprho_1,exprho_2,exprho_3$ and then take the natural logarithm
$endgroup$
– Shubham Johri
Dec 18 '18 at 12:54