How to plot two variables of a function having four variables?

I have a function

f = equv_sigma-Yref==0

with

 equv_sigma= (    (a*(r+w)^(2*k))    +    (a*(r-w)^(2*k))    +   ((1-a)*(2*A)^(2*k))   )^(1/(2*k));

with 3 terms

 r=(i+M*j)/2;
 w=sqrt((((N*i-P*j)^2)/4)+ ((Q^2)*ii*jj)  );
 A=sqrt((((R*i-S*j)^2)/4)+ ((T^2)*ii*jj)  );

with the following constants

a=0.543404;
M=1.093992;
N=1.018431;
P=0.972750;
Q=1.045567;
R=0.988196;
S=1.040132;
T=1.004799;
k=4;
Yref=142;

===========================

what I want is to plot the i and j values, so could you please help me? I HAVE TRIED TO PRODUCE THE i and j VALUES BUT NO CHANCE SICNE THE NESTED LOOP ARE HUGE.

=====================================

clear all

x=0;
y=0;
counter=0;
a=0.543404;
M=1.093992;
N=1.018431;
P=0.972750;
Q=1.045567;
R=0.988196;
S=1.040132;
T=1.004799;
k=4;
Yref=142;

for i=-150:0.01:-150 & 150:0.01:150
    for j=-150:0.01:-150 & 150:0.01:150
        r=(i+M*j)/2;
        for ii=-150:0.01:-150 & 150:0.01:150
            for jj=-150:0.01:-150 & 150:0.01:150
                w=sqrt((((N*i-P*j)^2)/4)+ ((Q^2)*ii*jj)  );
                A=sqrt((((R*i-S*j)^2)/4)+ ((T^2)*ii*jj)  );
                equv_sigma= (    (a*(r+w)^(2*k))    +    (a*(r-w)^(2*k))    +   ((1-a)*(2*A)^(2*k))   )^(1/(2*k));
                if  equv_sigma-Yref==0
                    counter=counter+1;
                    x(counter)=i;
                    y(counter)=j;
                end
            end            
        end

      end
  end

[Walter Roberson]

What is

for i=-150:0.01:-150 & 150:0.01:150

intended to mean?

Answer 1

[HAMZAH ALHARTHI]

sorry I made a mistake , this is the code I have tried clear all

x=0; y=0; counter=0; a=0.543404; M=1.093992; N=1.018431; P=0.972750; Q=1.045567; R=0.988196; S=1.040132; T=1.004799; k=4; Yref=142;

for i=-150:0.0001:150 for j=-150:0.0001:150 r=(i+M*j)/2; for ii=-150:0.0001:150 for jj=-150:0.0001:150 w=sqrt((((N*i-P*j)^2)/4)+ ((Q^2)*ii*jj) ); A=sqrt((((R*i-S*j)^2)/4)+ ((T^2)*ii*jj) ); equv_sigma= ( (a*(r+w)^(2*k)) + (a*(r-w)^(2*k)) + ((1-a)*(2*A)^(2*k)) )^(1/(2*k)); if equv_sigma-Yref==0 counter=counter+1; x(counter)=i; y(counter)=j; end end end

    end
end