MATLAB: Error: File: Untitled11.m Line: 1 Column: 10 Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

numerical methods

f = x^3+2x^2-x+3;
%actual derivative of function 
fprime = 3x^2+4x-1;
 
%step size:
 h=0.1;
 
 %forward difference
 dfdx_forward = f(1+h)-f(1)/h
 Error_forward = fprime(1)-dfdx_forward %error


 %backward difference
 dfdx_backward = (f(1)-f(1-h))/h
Error_backward = fprime(1)-dfdx_backward %error
 
%central difference
dfdx_central = (f(1+h)-f(1-h))/(2*h)
Error_central = fprime(1)-dfdx_central %error

Best Answer

f = x^3+2*x^2-x+3;
      %  ^---missing
fprime = 3*x^2+4*x-1;
      %   ^---missing

Related Solutions

MATLAB: Forward, backward and central differences

Fun = @(x) exp(-x).*sin(3*x); 
dFun = @(x) -exp(-x).*sin(3*x)+ 3*exp(-x).*cos(3*x);
x=linspace(0,4,101);
F=Fun(x);
h=x(2)-x(1);
xCentral=x(2:end-1);
dFCenteral=(F(3:end)-F(1:end-2))/(2*h);
xForward=x(1:end-1);
dFForward=(F(2:end)-F(1:end-1))/h;
xBackward=x(2:end);
dFBackward=(F(2:end)-F(1:end-1))/h;
plot(x,dFun(x));
hold on
plot(xCentral,dFCenteral,'r')
plot(xForward,dFForward,'k');
plot(xBackward,dFBackward,'g');
legend('Analytic','Central','Forward','Backward')

MATLAB: Discontinuity missing.

Connected lines 
x=-1:0.01:1;
y(x>=-1 & x<0)=-1-x(x>=-1 & x<0);
y(x>=0 & x<=1)=1-x(x>=0 & x<=1);
plot(x,y)

Alternative, not connected lines

x1=-1:0.01:0-0.01;
x2=0:0.01:1;
y1(x1>=-1 & x1<0)=-1-x1(x1>=-1 & x1<0);
y2(x2>=0 & x2<=1)=1-x2(x2>=0 & x2<=1);
plot(x1,y1)
hold on
plot(x2,y2,'r')

Best Answer

Related Solutions

MATLAB: Forward, backward and central differences

MATLAB: Discontinuity missing.

Related Question