interp2 error non monotonus

Hello i am facing problem with interp2

i have rpm , torque , efficiency values of motor i need to get eff using interp2

 for i=1
    torque_motor=data(:,1);
    rpm_motor=rpm;
    eff_motor=data;
    end
    for i=1:1:length(torque_motor)
        for j=1:1:length(rpm_motor)
            for k=1:1:length(data)
            temp1=find(torque_motor(:,k)==torque_array(i));
            temp2=find(rpm_motor(:,k)==rpm_array(j));
            [val,pos]=intersect(temp1,temp2);
            
             eff_epk=column_eff(val)
             i=i+1
             j=j+1
             k=k+1
            end
            end
        end
    end
eff_epk
[ttorque,rrpm]=meshgrid(torque_array,rpm_array)
ttorque=ttorque';
rrpm=rrpm';
for i=1:length(t)
EPK_operating=interp2(rrpm,ttorque,eff_epk,Nm,tm)
end

[Jan]

This is very confusing:

  i=i+1
  j=j+1
  k=k+1  

It is useless for the loop counter k, because the FOR command ignores changes of its counter inside the loop. But here you change the counters of the outer loops also. Is this really wanted?

You are overwriting the value of eff_epk in each iteration. Is this really wanted?

The body of the final loop does not depend on the loop counter i .

Finally the readers have to guess, which line is failing with which error message. Please post a copy of the complete message. As long, as you do not explain, what the code should do, and the code fails, the readers have to guess the intention of the code.

I guess, that the message you see means, that the input data of interp2 are non strict monotonically increasing.

[KSSV]

WE cannot help unless data is known to us.

[Harish Vernekar]

[Harish Vernekar]

here is the data we have rpm on x axis and torque on y axis i have to interpolate a look up table to get the values for the calculated torque and RPM values

Answer 1

[Bjorn Gustavsson]

It should (big claim, I know) be as simple as:

torque = data(2:end,1);
rpm = data(1,2:end);
eff_epk = data(2:end,2:end);
Nm = [2^.5 exp(-1), pi, exp(2)]; % You'll have more sensible parameters here...
tm = [3 30 300 3000]; 
EPK_operating=interp2(rrpm,ttorque,eff_epk,Nm,tm);

HTH

[Harish Vernekar]

thank you