For Ronald Reagan, it was a week of high drama and deep emotions, a week in which he grasped the reins of government and developed a new appreciation for the man he defeated last November.

And for his new administration, it was a week in which the White House staff struggled to gain control of the great engine that is the federal government, and also a week in which the initial signs of conflict appeared between that staff and the president's Cabinet.

The week offered glimpses of a fledgling president who will be 70 years old next week but at times seemed almost boyish in his enthusiasm for his new job. It was a Reagan outraged by Iranian mistreatment of the hostages, exhilarated by the response at his first Cabinet meeting and disappointed that the stock market slumped after his inaugural address.

"Don't worry, Mr. President," said Treasury Secretary Donald T. Regan, a former stockbroker. "The stock market has gone down after every inauguration except Kennedy's."

"This time it went down because all the buyers were in Washington," chimed in an aide, to laughter from the president.

But the president wasn't laughing when talk turned to the returning hostages, as it did repeatedly during his first week in office. Reagan told one aide how proud he was of the patriotism of the hostages, comparing their fortitude and courage to that of former prisoners of war in Vietnam whom he and Nancy Reagan once hosted at their California home.

And Reagan, who in his inaugural speech expressed gratitude to former president Carter for the courtesy he displayed in the transition, showed that he was fully capable of a graceful, appropriate gesture to his defeated political foe.

Aides told Reagan on Inauguration Day that Carter wanted to go to Germany to greet the returning hostages. Instead of simply letting Carter go, Reagan promptly decided to send him as the official representative of the nation. He told Carter this in a telephone conversation a few moments later.

"The president was deeply appreciative of the way President Carter had behaved during the transition week, and he shared a deep concern for the hostages," said a Reagan official. "He also realizes that the ex-presidents' club is a most exclusive one."

When Reagan was governor of California, particularly at first, he sometimes seemed uninterested in the mechanics and processes of the office.

This wasn't true in the White House the first week, where the new president took delight in everything from presiding over the Cabinet to locating the stewards' quarters so he could get an extra cup of coffee.

"the president is totally engaged in the process," said White House chief of staff James A. Baker after Reagan had chaired a Cabinet meeting without aid from his senior staff.

While Reagan was reveling, the first glimmers of struggle between departments and the White House staff became visible. On the second day of the Reagan presidency, Secretary of State Alexander M. Haig Jr. presented some proposed executive orders for Reagan's signature which would have transferred some foreign policy functions of other departments to State.

The orders failed to clear Baker's desk, however, as the White House team of Baker and counselor Edwin Meese III displayed a quiet exercise of authority.

That staff also was struggling with the difficult task of speeding Reagan's lagging timetable on sub-Cabinet and other political appointments.

"Frankly, it's taken us longer than we wanted it to or than it should have taken," said a Reagan aide.

The aide said that security and ethics checks had taken longer than anticipated. But he acknowledged that the intense interest of Reagan's "kitchen cabinet" in the major appointments also had delayed the process.

Two millionaire southern California businessmen, Holmes Tuttle and Justin Dart, are leading members of this unofficial advisory group. So is William French Smith, the Los Angeles lawyer whom Reagan named attorney general.

The too-deliberate speed of the appointments process was the administration's biggest headache. A close second was the increasing internal pressure on the administration from conservative groups who feel their choices were passed over for high Cabinet posts.

This has moved the struggle between pragmatists and ideologues to the less visible but sometimes equally important deputy secretary level where so many of the practical policy decisions which run the engine of government are made.

One Reagan political operative discussed this problem in terms similar to those used by the criminal leader in "The Godfather," when he advised: "Hold your friends close; hold your enemies close." The Reagan backer put it this way: "We want to keep the Moral Majority types so close to us they can't move their arms."

He went on to say that it was important for the administration to give this faction something so they wouldn't turn on the president.

"What do you want to give them?" a reporter asked.

"Symbolism," the Reagan operative replied.

This is exactly what Reagan did Thursday, when he gave an anti-abortion group, the March for Life, the distinction of being the first non-governmental group to have a presidential audience. In so doing, Reagan was giving moral support to the anti-abortion constitutional amendment he frequently endorsed during the election campaign.

Beyond this symbolism, it was unclear what the political direction of the White House would be during the first weeks of the Reagan administration. Former press director Lyn Nofziger came aboard in the week to serve as a political assistant, with some seeing his role as primarily an emissary to conservatives and others envisioning a much broader role. When Nofziger was asked by one Reagan backer what he considered to be political, he reportedly replied, "Everything."

These maneuverings, however, occurred far below the rim of Reagan's gaze.

While the White House was getting organized, and the chief figures in the administration were sorting out their roles, Reagan was operating on the euphoric high of a week in which he became president and Iran released the American hostages.

"It was a good first week," said an aide, accurately.

But there are less exhilarating weeks ahead.