Keeping getting gradient error and no figure 2

function [] =ZacharyC1
clear all 
clc
U=4.7;
m=6;
a=0.5;
[X,Y]=meshgrid (-2:0.05:-2,2:0.05:2); 
r=sqrt(X.^2+Y.^2); 
THETA=atan2(Y,X);
THETA1=atan2(Y,X+a);
THETA2=atan2(Y,X-a); 
psi=U*r.*sin(THETA)+m*(THETA1-THETA2);
[DX,DY]=gradient(psi,.1,.1);
u=DY;
v=-DX;
contour (X,Y,psi,21);
hold on
quiver(X,Y,u,v,4)
hold off
[mm,nn]=size(u);
nnn=round(nn/3);
for i=1:mm
    p(i,nnn)=0.5*U*U-0.5*(u(i,nnn)^2);
end
plot(p(:,nnn))
end

Answer 1

[VBBV]

%function [] =ZacharyC1
clear all 
clc
U=4.7;
m=6;
a=0.5;
[X,Y]=meshgrid (linspace(-2,2,100),linspace(-2,2,100)); 
r=sqrt(X.^2+Y.^2); 
THETA=atan2(Y,X);
THETA1=atan2(Y,X+a);
THETA2=atan2(Y,X-a); 
psi=U*r.*sin(THETA)+m*(THETA1-THETA2)

psi = 100x100

-7.8847 -7.8541 -7.8230 -7.7913 -7.7591 -7.7263 -7.6930 -7.6592 -7.6248 -7.5901 -7.5548 -7.5192 -7.4831 -7.4467 -7.4100 -7.3730 -7.3358 -7.2983 -7.2608 -7.2232 -7.1856 -7.1480 -7.1106 -7.0733 -7.0364 -6.9998 -6.9636 -6.9280 -6.8929 -6.8586 -7.6941 -7.6629 -7.6311 -7.5986 -7.5656 -7.5320 -7.4978 -7.4631 -7.4278 -7.3920 -7.3557 -7.3189 -7.2817 -7.2441 -7.2061 -7.1678 -7.1293 -7.0905 -7.0515 -7.0124 -6.9733 -6.9342 -6.8952 -6.8564 -6.8178 -6.7796 -6.7418 -6.7045 -6.6678 -6.6318 -7.5042 -7.4723 -7.4397 -7.4065 -7.3727 -7.3383 -7.3032 -7.2675 -7.2312 -7.1944 -7.1570 -7.1191 -7.0807 -7.0419 -7.0026 -6.9630 -6.9230 -6.8828 -6.8424 -6.8018 -6.7611 -6.7204 -6.6797 -6.6392 -6.5989 -6.5590 -6.5194 -6.4804 -6.4419 -6.4042 -7.3149 -7.2823 -7.2490 -7.2151 -7.1805 -7.1451 -7.1092 -7.0725 -7.0352 -6.9974 -6.9589 -6.9198 -6.8802 -6.8401 -6.7995 -6.7585 -6.7171 -6.6753 -6.6333 -6.5912 -6.5488 -6.5064 -6.4641 -6.4218 -6.3797 -6.3380 -6.2966 -6.2557 -6.2154 -6.1758 -7.1263 -7.0930 -7.0590 -7.0243 -6.9889 -6.9527 -6.9158 -6.8782 -6.8399 -6.8009 -6.7613 -6.7210 -6.6802 -6.6387 -6.5968 -6.5543 -6.5114 -6.4681 -6.4245 -6.3807 -6.3366 -6.2925 -6.2483 -6.2042 -6.1602 -6.1165 -6.0732 -6.0304 -5.9881 -5.9465 -6.9384 -6.9045 -6.8698 -6.8343 -6.7980 -6.7610 -6.7231 -6.6846 -6.6452 -6.6051 -6.5643 -6.5228 -6.4807 -6.4379 -6.3945 -6.3506 -6.3062 -6.2613 -6.2160 -6.1704 -6.1246 -6.0786 -6.0325 -5.9864 -5.9405 -5.8948 -5.8494 -5.8045 -5.7601 -5.7164 -6.7513 -6.7167 -6.6813 -6.6450 -6.6080 -6.5700 -6.5313 -6.4917 -6.4513 -6.4101 -6.3681 -6.3253 -6.2819 -6.2377 -6.1928 -6.1474 -6.1013 -6.0548 -6.0078 -5.9604 -5.9127 -5.8647 -5.8167 -5.7686 -5.7205 -5.6727 -5.6251 -5.5780 -5.5314 -5.4855 -6.5651 -6.5298 -6.4937 -6.4566 -6.4187 -6.3799 -6.3402 -6.2996 -6.2581 -6.2158 -6.1726 -6.1286 -6.0837 -6.0381 -5.9918 -5.9447 -5.8970 -5.8488 -5.7999 -5.7507 -5.7010 -5.6510 -5.6009 -5.5506 -5.5004 -5.4503 -5.4004 -5.3509 -5.3020 -5.2537 -6.3797 -6.3438 -6.3069 -6.2691 -6.2304 -6.1907 -6.1500 -6.1084 -6.0659 -6.0224 -5.9779 -5.9326 -5.8864 -5.8393 -5.7914 -5.7428 -5.6933 -5.6433 -5.5926 -5.5413 -5.4896 -5.4375 -5.3852 -5.3327 -5.2801 -5.2276 -5.1753 -5.1234 -5.0719 -5.0211 -6.1952 -6.1586 -6.1211 -6.0825 -6.0430 -6.0024 -5.9608 -5.9182 -5.8745 -5.8299 -5.7842 -5.7375 -5.6899 -5.6413 -5.5919 -5.5415 -5.4903 -5.4384 -5.3857 -5.3324 -5.2786 -5.2243 -5.1697 -5.1148 -5.0598 -5.0048 -4.9499 -4.8953 -4.8412 -4.7877

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[DX,DY]=gradient(psi,.1);
u=DY;
v=-DX;
contour (X,Y,psi,21);
hold on
quiver(X,Y,u,v,4)
hold off

[mm,nn]=size(u);
nnn=round(nn/3);
for i=1:mm
    p(i,nnn)=0.5*U*U-0.5*(u(i,nnn)^2);
end
plot(p(:,nnn))

%end

[VBBV]

Use linspace for generation of datagrid points.

[Zachary]

Thank you. I got figure 1, but how do I find figure 2. It didn't pop up.