'ReturnConditions' creates error in 'solve'
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Hi! I am trying to solve the following system of equations analytically. Matlab can't solve the general case (in which phi is not specified) so I set its value to -1.
syms i1 i2 gamma phi w r
firstfoc=( (2+r)*w/(1+r) ) * ...
(gamma*i1^phi + (1-gamma)*i2^phi)^(1/phi)*gamma*i1^(phi-1)==1+r
secondfoc=((2+r)*w/(1+r) ) * ...
(gamma*i1^phi + (1-gamma)*i2^phi)^(1/phi)*(1-gamma)*i2^(phi-1)==1
firstfoc=subs(firstfoc,phi,-1)
secondfoc=subs(firstfoc,phi,-1)
[i1sol, i2sol]=solve(firstfoc, secondfoc, i1, i2)
[i1sol, i2sol]=solve(firstfoc, secondfoc, i1, i2,'ReturnConditions',true)
As you can see, the first call to "solve" returns an answer, but warns that it's parameter-dependent and advises setting 'ReturnConditions' to true. However, doing so causes a rather opaque error. What's going on here, and is there an easy way to tell over what regions in the (gamma, w, r) parameter space there is a solution?
Any help would be greatly appreciated!
采纳的回答
Provide output variables, and outputs to return the parameters and conditions:
syms i1 i2 gamma phi w r
firstfoc=( (2+r)*w/(1+r) ) * ...
(gamma*i1^phi + (1-gamma)*i2^phi)^(1/phi)*gamma*i1^(phi-1)==1+r
secondfoc=((2+r)*w/(1+r) ) * ...
(gamma*i1^phi + (1-gamma)*i2^phi)^(1/phi)*(1-gamma)*i2^(phi-1)==1
firstfoc=subs(firstfoc,phi,-1)
secondfoc=subs(firstfoc,phi,-1)
[i1sol, i2sol]=solve(firstfoc, secondfoc, i1, i2)
[isol1, isol2, parms, condx]=solve(firstfoc, secondfoc, [i1,i2], 'ReturnConditions',true)
.
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