Substitution of symbols in equation after their values are being calculated

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inzamam shoukat
inzamam shoukat 2024-3-21
评论： Star Strider 2024-3-22
i have Fallowing Equation
syms yApprox(X1) a0 a1 a2 a3 a4 a5 a6
yApprox = a0 + a1*X1 + a2*X1^2 + a3*X1^3+ a4*X1^4 + a5*X1^5 + a6*X1^6;
i have calculated values of a0 a1 a2 a3 a4 a5 a6, In order to express the equation in therms of these values Now i want to substitute them in equation how i can do that???

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Star Strider
Star Strider 2024-3-21
Ran in:
Try this —
syms yApprox(X1) a0 a1 a2 a3 a4 a5 a6
syms a2 a3 a4 a5 a6
EQ_01=a2 +9*a3 + 72*a4 + 540*a5 + 3888*a6 == -121/36000;
EQ_02=a3+ a2/12 +9*a4 +72*a5 +540*a6 == -1049/7776000;
EQ_03=a4 + (5*a2)/648 + (5*a3)/48 + (25*a5)/3 + (450*a6)/7 == -2987/419904000;
EQ_04 =a5 + (7*a2)/8640 + (7*a3)/600 + (7*a4)/60 + (63*a6)/8 == -19789/41990400000;
EQ_05 =a6 + a2/10800 + a3/720 + a4/70 + a5/8 == -24163/661348800000;
sol = solve([EQ_01, EQ_02, EQ_03, EQ_04, EQ_05],[a2,a3,a4,a5,a6])
sol = struct with fields:
a2: -265660443171156185011/26563311466141754327040 a3: 36806947866579283561/39844967199212631490560 a4: 8376188234952364463/956279212781103155773440 a5: -76519827268723512571/14344188191716547336601600 a6: 21255507574645885373/143441881917165473366016000
a2 = vpa(sol.a2)
a2 = 
a3 = vpa(sol.a3)
a3 = 
0.00092375400091448985737373823903909
a4 = vpa(sol.a4)
a4 = 
0.0000087591449474178977579770895298368
a5 = vpa(sol.a5)
a5 = 
a6 = vpa(sol.a6)
a6 = 
0.00000014818201832377291812525209972859
yApprox = a0 + a1*X1 + a2*X1^2 + a3*X1^3+ a4*X1^4 + a5*X1^5 + a6*X1^6;
yApprox = subs(yApprox)
yApprox = 
yApprox = vpa(yApprox, 6) % Easier To Read, Retains Full Precison
yApprox = 
Use the subs funciton to automatically (in this instance) substitute the appropriate variables.
.

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