CODEWITHSUNDEEP
for-loopscilab
Dr.mark
Dr.mark

Reputation: 49

How can I get the output as a scalar value not a vector from this function?

I am writing a function to find the definite integral of any function by using the Midpoint method, the output of this function must be a scalar value, where y(k+1)=dt*(f(t0+dt/2)+...+f(t(k)+dt/2)) this is the main idea of the Midpoint method and after calculating y(k+1) by using the for loop, it returns a scalar value of this integration, but I found that this function returns the output as a vector y which means it gives all values from y(1) to y(k+1). the exact value of this integration=14/3 which is very close to y(26) in the output vector. How can I get the output as a scalar value y(26) not a vector?

clear
//Midpoint integral
function [t,y]=Midpoint_Int(f,tinterval,n)
    y=zeros(n+1,1);  // preallocation of y
    y(1)=0;   //initial condition   y(1)=y0=0
    dt=(tinterval(2)-tinterval(1))/n;
    t=tinterval(1):dt:tinterval(2);
    for k=1:n
        m2=f(t(k)+dt/2)
        y(k+1)=y(k)+dt*m2;
    end
    t=t';
endfunction

function a=f(x)
    a=1+x^2
endfunction
[t,y]=Midpoint_Int(f,[0,2],25)

Upvotes: 0

Views: 88

Answers (1)

Serge Steer
Serge Steer

Reputation: 446

Just modify your function this way

function [t,y]=Midpoint_Int(f,tinterval,n)
  y=0;   //initial condition 
  dt=(tinterval(2)-tinterval(1))/n;
  t=tinterval(1):dt:tinterval(2);
  for k=1:n
    m2=f(t(k)+dt/2)
    y=y+dt*m2;
  end
  t=t';
endfunction

Upvotes: 1

Related Questions