rce={200==15*(10^(-4))*(5*(T-20)+5.66*(10^(-8))*0.4*((((T+273))^4)-(293^4)))};

res=Solve[rce,T]

Cases[{1,2,3.5,4,5},_Integer?(#>3&)]

Cases[T/.res,_?(#>0&)]//Quiet

FindRoot[rce,{T,-2000+25I}]

((x/.FindRoot[Sin[x]==0,{x,(Pi/2)}])/Pi)

fcePolynom[n_]:=Plus@@Table[(Subscript[a, i])*(x^i),{i,0,n}]==0

Solve[fcePolynom[5],x]

rce1pokus={200==15*(10^(-4))*(5*(Ti1-20)+5.66*(10^(-8))*0.4*(((Ti+273))^4)-(293^4))};

res2=Solve[rce1pokus,Ti1]

fce1pokus[Ti_]:=Evaluate[Ti1/.res2[[1]]]

fce1pokus[3]

NestList[fce1pokus,3,5]

rce2=200==15*(10^(-4))*(5*(Ti-20)+5.66*(10^(-8))*0.4*(aa-(293^4)))

aaa=aa/.Solve[rce2,aa][[1]]

fce2pokus[Ti_]:=Evaluate[(aaa^(1/4))-273]
NestList[fce2pokus,3,5]

leva=rce[[1,1]];
prava=rce[[1,2]];
fceMin=(((prava-leva))^2)

FindMinimum[fceMin,{T,200}]

Acka={{2500,25,0.015},{3000,20,0.13},{1500,27,0.05},{10,10,1}};

PminMax={{150,250},{900,1100},{600,900},{0,200}};

Plot[(((Tanh[100(x-2)]+1)/2)-((Tanh[100(x+2)]+1)/2))+1,{x,-5,5}]

fceInterval[a_,b_,el_]:=2*(1-(((-((Tanh[100((Subscript[P, el])-b)]+1)/2)+((Tanh[100((Subscript[P, el])-a)]+1)/2))+1)/2))

fceEl[el_]:=Plus@@Table[((Subscript[P, el])^(i-1))*Acka[[1,i]],{i,1,3}]+(10^20)fceInterval[PminMax[[el,1]],PminMax[[el,2]],el]

fceEl[1]

Plot[fceEl[1],{(Subscript[P, 1]),0,300}]

Acka[[1,3]]

fceVse=Plus@@Table[fceEl[i],{i,1,4}]

fceMinnn[Pzadany_]:=fceVse+(((Pzadany-Evaluate[Plus@@Table[(Subscript[P, i]),{i,1,4}]]))^2)

FindMinimum[fceMinnn[1500],{{(Subscript[P, 1]),200},{(Subscript[P, 2]),1000},{(Subscript[P, 3]),750},{(Subscript[P, 4]),100}}]