A Three-Term Gradient Descent Method with Subspace Techniques

Algorithm 1

TCGS.

	Step 1: given and , set and .
	Step 2: if holds, then stop; else, go to step 3.
	Step 3: determine the step-size by Wolfe line search, which means that conditions (4) and (5) hold.
	Step 4: generate by using the acceleration scheme [33], and compute , , and .
	Step 5: if dim() = 2, compute by (21), and go to step 6. If dim() = 3, compute by (10) and (17), and go to step 6.
	Step 6: set , and go to step 2.