title: Multiply matrix columns with decreasing elements starting by the last column
body: <p>I have a matrix with following shape:</p>
  
  <pre><code>A = [1 2 3;
       4 5 6;
       7 8 9]
  </code></pre>
  
  <p>Now I want starting with the last column to multiply the column with a number and then decrease the number and move to the next column.</p>
  
  <p>So if we start with the number 1 and use for step 0.2 to modify all columns:</p>
  
  <pre><code>Anew = [1*0.6 2*0.8 3*1;
          4*0.6 5*0.8 6*1;
          7*0.6 8*0.8 9*1]
  </code></pre>
  
  <p>Or for second example we start with 0.9 with 0.1 as step and modify 3 columns:</p>
  
  <pre><code>B = [1  2  3  4;
       5  6  7  8;
       9  10 11 12;
       13 14 15 16]
  </code></pre>
  
  <p>And to get:</p>
  
  <pre><code>Bnew = [1   2*0.7  3*0.8   4*0.9;
          5   6*0.7  7*0.8   8*0.9;
          9   10*0.7 11*0.8 12*0.9;
          13  14*0.7 15*0.8 16*0.9]
  </code></pre>
  
  <p>The matrices might vary in their amount of columns, and I would like to set starting number, ending number, step number and the amount of columns I want to modify.</p>