Can Someone help me solve what is wrong with this code

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Echo Lei
Echo Lei 2022-10-4
评论： VBBV 2022-10-6
Ran in:
%Use symbolic processing with the variable x
syms x
syms fp(x)
syms Increasing
syms Decreasing
syms Minimum
syms Maximum
syms Inflection
syms CP
%Enconde the function f(x)
f(x) =(1+x^2)/(1-x^2)
f(x) = 
%Set the distance to the left/right of the critical point
h=0.01
h = 0.0100
%Find the first derivative of the function
fp(x) = diff(1+(x^2))/(1-(x^2))
fp(x) = 
%Solve for the roots of fp
root1 = solve(fp,x)
root1 = 
0
%Consider the first critical point only
c=root1(1)
c = 
0
%Determine if the function is "Increasing" or "Decreasing" at the right of the critical point
if (fp(c+h)>0)
IoDR = "Increasing"
elseif (fp(c+h)<0)
IoDR = "Decreasing"
end
IoDR = "Increasing"
%Determine if the function is "Increasing" or "Decreasing" at the right of the critical point
if (fp(c-h)>0)
IoDL = "Decreasing"
elseif (fp(c-h)<0)
IoDL = "Increasing"
end
IoDL = "Increasing"
%Use first derivative Test to Determine if the critical point is a "Maximum" point or "Minimum" point.
if IoDL=="Increasing" & IoDR =="Decreasing"
CP= "Maximum"
elseif IoDL=="Decreasing" & IoDR =="Increasing"
CP= "Minimum"
end
%Find the second derivative of the function
fpp(x)= diff(f,2);
%Find the points of inflection of the function by equating the second derivative of the function to zero.
cc = diff(fp,x)
cc(x) = 
%Apply Second Derivative Test to check whether the critical point is a "Maximum" point, a "Minimum" point or "Point of Inflection".
if fpp(c) >0
CP2 = "Maximum"
elseif fpp(c)<0
CP2 = "Minimum"
else
CP2 = "Point of Inflection"
end
CP2 = "Maximum"
%GRAPH THE FUNCTION
clf();
g1= ezplot(f);
hold on
grid on
plot(c,f(c), 'r*')
title("Curve Tracing")
text(c+.5,f(c),["("+string(c)+","+string(f(c))+") "+CP ])
Error using sym>convertChar
Character vectors and strings in the first argument can only specify a variable or number. To evaluate character vectors and strings representing symbolic expressions, use 'str2sym'.

Error in sym>tomupad (line 1624)
S = convertChar(x);

Error in sym (line 397)
S.s = tomupad(x);

Error in sym/privResolveArgs (line 1184)
argout{k} = sym(arg);

Error in sym/privBinaryOp (line 1216)
args = privResolveArgs(A, B);

Error in + (line 7)
X = privBinaryOp(A, B, 'symobj::zipWithImplicitExpansion', '_plus');

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回答（1 个）

VBBV
VBBV 2022-10-4
编辑：VBBV 2022-10-4
%syms CP
Comment this line and try as CP is symbolic. Then you get know whether it's maximum or minimum
  3 个评论
显示 1更早的评论
VBBV
VBBV 2022-10-6
In the given code, the if-else condition for IoDL and IoDR variables are not satisfied since they are both increasing. so, output of CP will be unknown. In order to input CP, c and h needs to computed in such a way that condition is satisfied so that CP can be determined either as minimum or maximum strings.

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