MATLAB: How to plot two line in one figure

plotting

I'm working on this code and I want to plot the result for two values of XNP for example:
XNP=4 and 5
I tried to use (hold on) but it keeps giving me one line
n = 0;
VM = 881;
VT = 600;
XNT = 1;
HEDEG = -20;
XNP = 4;
RM1 = 0;
RM2 = 0;
RT1 = 40000;
RT2 = 10000;
BETA = 0.85;
VT1 = -VT*cos(BETA);
VT2 = VT*sin(BETA);
HE = HEDEG/57.3;
T = 0;
S = 0;
RTM1 = RT1 - RM1;
RTM2 = RT2 - RM2;
RTM = sqrt(RTM1*RTM1+RTM2*RTM2);
XLAM = atan2(RTM2,RTM1);
XLEAD = asin(VT*sin(BETA+XLAM)/VM);
THET = XLAM + XLEAD ;
VM1 = VM*cos(THET+HE);
VM2 = VM*sin(THET+HE);
VTM1 = VT1 - VM1;
VTM2 = VT2 - VM2;
VC = -(RTM1*VTM1+RTM2*VTM2)/RTM;
while VC >= 0
    if RTM < 1000
        H = 0.0002;
    else 
        H = 0.01;
    end
    BETAOLD = BETA;
    RT1OLD = RT1;
    RT2OLD =RT2;
    RM1OLD = RM1;
    RM2OLD = RM2;
    VM1OLD = VM1;
    VM2OLD = VM2;
    STEP = 1;
    FLAG = 0;
    while STEP <= 1
        if FLAG == 1
                  STEP = 2;
           BETA = BETA+H*BETAD;
           RT1 = RT1 +H*VT1;
           RT2 = RT2 +H*VT2;
           RM1 = RM1 +H*VM1;
           RM2 = RM2 +H*VM2;
           VM1 = VM1 +H*AM1;
           VM2 = VM2 +H*AM2;
           T=T+H;
        end
        RTM1=RT1-RM1;
            RTM2=RT2-RM2;
            RTM=sqrt(RTM1*RTM1+RTM2*RTM2);
            VTM1=VT1-VM1;
            VTM2=VT2-VM2;
            VC=-(RTM1*VTM1+RTM2*VTM2)/RTM;
            XLAM=atan2(RTM2,RTM1);
            XLAMD=(RTM1*VTM2-RTM2*VTM1)/(RTM*RTM);
            XNC=XNP*VC*XLAMD;
            AM1=-XNC*sin(XLAM);
            AM2=XNC*cos(XLAM);
            VT1=-VT*cos(BETA);
            VT2=VT*sin(BETA);
            BETAD=XNT/VT;
        FLAG=1;
    end
    FLAG=0;
    BETA=.5*(BETAOLD+BETA+H*BETAD);
    RT1=.5*(RT1OLD+RT1+H*VT1);
    RT2=.5*(RT2OLD+RT2+H*VT2);
    RM1=.5*(RM1OLD+RM1+H*VM1);
    RM2=.5*(RM2OLD+RM2+H*VM2);
    VM1=.5*(VM1OLD+VM1+H*AM1);
    VM2=.5*(VM2OLD+VM2+H*AM2);
    S=S+H;
    if S >=.09999
            S=0.;
        n=n+1;
        ArrayT(n)=T;
        ArrayRT1(n)=RT1;
        ArrayRT2(n)=RT2;
        ArrayRM1(n)=RM1;
        ArrayRM2(n)=RM2;
        ArrayXNCG(n)=XNC/32.2;
        ArrayRTM(n)=RTM;
    end
end
RTM
figure
plot(ArrayRT1,ArrayRT2,ArrayRM1,ArrayRM2),grid
title('Two-dimensional tactical missile-target engagement simulation')
xlabel('Downrange (Ft) ')
ylabel('Altitude (Ft)')
figure
plot(ArrayT,ArrayXNCG),grid
title('Two-dimensional tactical missile-target engagement simulation')
xlabel('Time (sec)')
ylabel('Acceleration of missle (G)')
clc
output=[ArrayT',ArrayRT1',ArrayRT2',ArrayRM1',ArrayRM2',ArrayXNCG',ArrayRTM' ];
save datfil.txt output
disp '*** Simulation Complete'

Best Answer

Hi,
If you want the plots for different values of XNP to appear on the same graph, instead of using figure, number your figures as figure(1) and figure(2). You were correct when you were using hold on and hold off. By numbering your figure, when you change the value of XNP to 5 from 4, the new line will be overlap the plot generated when XNP = 4. Make sure that you do not close the plots generated when XNP = 4. A better method would be to modify your code so that XNP is a vector of values.
I have pasted the modified code below. Look at the comments at the bottom of the code to see the changes.
n = 0;
VM = 881;
VT = 600;
XNT = 1;
HEDEG = -20;
XNP = 5;
RM1 = 0;
RM2 = 0;
RT1 = 40000;
RT2 = 10000;
BETA = 0.85;
VT1 = -VT*cos(BETA);
VT2 = VT*sin(BETA);
HE = HEDEG/57.3;
T = 0;
S = 0;
RTM1 = RT1 - RM1;
RTM2 = RT2 - RM2;
RTM = sqrt(RTM1*RTM1+RTM2*RTM2);
XLAM = atan2(RTM2,RTM1);
XLEAD = asin(VT*sin(BETA+XLAM)/VM);
THET = XLAM + XLEAD ;
VM1 = VM*cos(THET+HE);
VM2 = VM*sin(THET+HE);
VTM1 = VT1 - VM1;
VTM2 = VT2 - VM2;
VC = -(RTM1*VTM1+RTM2*VTM2)/RTM;
while VC >= 0
  if RTM < 1000
      H = 0.0002;
  else 
      H = 0.01;
  end
  BETAOLD = BETA;
  RT1OLD = RT1;
  RT2OLD =RT2;
  RM1OLD = RM1;
  RM2OLD = RM2;
  VM1OLD = VM1;
  VM2OLD = VM2;
  STEP = 1;
  FLAG = 0;
  while STEP <= 1
      if FLAG == 1
                STEP = 2;
         BETA = BETA+H*BETAD;
         RT1 = RT1 +H*VT1;
         RT2 = RT2 +H*VT2;
         RM1 = RM1 +H*VM1;
         RM2 = RM2 +H*VM2;
         VM1 = VM1 +H*AM1;
         VM2 = VM2 +H*AM2;
         T=T+H;
      end
      RTM1=RT1-RM1;
          RTM2=RT2-RM2;
          RTM=sqrt(RTM1*RTM1+RTM2*RTM2);
          VTM1=VT1-VM1;
          VTM2=VT2-VM2;
          VC=-(RTM1*VTM1+RTM2*VTM2)/RTM;
          XLAM=atan2(RTM2,RTM1);
          XLAMD=(RTM1*VTM2-RTM2*VTM1)/(RTM*RTM);
          XNC=XNP*VC*XLAMD;
          AM1=-XNC*sin(XLAM);
          AM2=XNC*cos(XLAM);
          VT1=-VT*cos(BETA);
          VT2=VT*sin(BETA);
          BETAD=XNT/VT;
      FLAG=1;
  end
  FLAG=0;
  BETA=.5*(BETAOLD+BETA+H*BETAD);
  RT1=.5*(RT1OLD+RT1+H*VT1);
  RT2=.5*(RT2OLD+RT2+H*VT2);
  RM1=.5*(RM1OLD+RM1+H*VM1);
  RM2=.5*(RM2OLD+RM2+H*VM2);
  VM1=.5*(VM1OLD+VM1+H*AM1);
  VM2=.5*(VM2OLD+VM2+H*AM2);
  S=S+H;
  if S >=.09999
          S=0.;
      n=n+1;
      ArrayT(n)=T;
      ArrayRT1(n)=RT1;
      ArrayRT2(n)=RT2;
      ArrayRM1(n)=RM1;
      ArrayRM2(n)=RM2;
      ArrayXNCG(n)=XNC/32.2;
      ArrayRTM(n)=RTM;
  end
end
RTM
hold on % Added to plot multiple lines
figure(1); % Number your figure

plot(ArrayRT1,ArrayRT2,ArrayRM1,ArrayRM2),grid ON % It is better to use grid ON
title('Two-dimensional tactical missile-target engagement simulation')
xlabel('Downrange (Ft) ')
ylabel('Altitude (Ft)')
hold off
hold on
figure(2); % Number your figure
plot(ArrayT,ArrayXNCG),grid ON
title('Two-dimensional tactical missile-target engagement simulation')
xlabel('Time (sec)')
ylabel('Acceleration of missle (G)')
hold off
clc
output=[ArrayT',ArrayRT1',ArrayRT2',ArrayRM1',ArrayRM2',ArrayXNCG',ArrayRTM' ];
save datfil.txt output
disp '*** Simulation Complete'
Related Question